Method of preparing diisocyanate composition

ABSTRACT

The embodiments provide processes for preparing a diisocyanate composition and an optical lens, which are excellent in yield and quality with mitigated environmental problems by using a solid triphosgene composition instead of phosgene gas in the process of preparing a diisocyanate from a diamine through a hydrochloride thereof and by controlling the content of a decomposition product in a triphosgene composition, the b* value according to CIE color coordinate of the triphosgene composition in an organic solvent, or the content of water in the triphosgene.

TECHNICAL FIELD

Embodiments relate to a process for preparing a diisocyanatecomposition. More specifically, the embodiments relate to a process forpreparing a diisocyanate composition through a diamine hydrochloride, aprocess for preparing an optical lens using the diisocyanate compositionthus prepared, and a triphosgene composition having a specific contentof components and used in the above preparation.

BACKGROUND ART

Isocyanates used as a raw material for plastic optical lenses areprepared by a phosgene method, a non-phosgene method, a pyrolysismethod, or the like.

In the phosgene method, an amine as a raw material is reacted withphosgene (COCl₂) gas to synthesize an isocyanate. In addition, in thenon-phosgene method, xylylene chloride is reacted with sodium cyanate inthe presence of a catalyst to synthesize an isocyanate. In the pyrolysismethod, an amine is reacted with an alkyl chloroformate to prepare acarbamate, which is pyrolyzed in the presence of a catalyst at a hightemperature to synthesize an isocyanate.

The phosgene method among the above methods for preparing isocyanates isthe most widely used. In particular, a direct method in which an amineis directly reacted with phosgene gas has been commonly used. But it hasa problem that a plurality of apparatuses for the direct reaction ofphosgene gas are required. Meanwhile, in order to supplement the directmethod, a hydrochloride method has been developed in which an amine isreacted with hydrogen chloride gas to obtain an amine hydrochloride asan intermediate, which is reacted with phosgene, as disclosed in KoreanPatent Publication No. 1994-1948.

In the method of obtaining hydrochloride as an intermediate by reactingan amine with hydrogen chloride gas among the conventional phosgenemethods for synthesizing isocyanates, a hydrochloride is produced asfine particles at atmospheric pressure, so that the agitation inside thereactor is not smoothly carried out. Thus, an additional process ofraising the temperature to increase the pressure inside the reactor isrequired, and there is a problem that the yield of the final product islow as well.

Thus, an attempt has been made to obtain a hydrochloride using anaqueous hydrochloric acid solution instead of hydrogen chloride gas.However, as the amine is dissolved in the aqueous hydrochloric acidsolution, the yield is significantly reduced to 50%, making it difficultto be applied in practice. There is a difficulty in that an amine havinga low content of water and impurities should be used as a raw materialin order to increase the purity of the final product. In addition,phosgene gas used in the conventional phosgene method is highly toxicand is a substance subject to environmental regulations. There is adifficulty in storage and management since a separate cooling apparatusis required to store it.

DETAILED DESCRIPTION OF THE INVENTION Technical Problem

Accordingly, the present inventors have been able to solve theconventional environmental, yield, and quality problems in the processof preparing a diisocyanate, which is mainly used as a raw material forplastic optical lenses, from a diamine through a hydrochloride thereofby way of using an aqueous hydrochloric acid solution instead ofhydrogen chloride gas and solid triphosgene instead of phosgene gaswhile adjusting the reaction conditions.

In addition, the present inventors have focused that triphosgene is inpart decomposed by various causes such as air, metal salt, silica gel,dust, heat, and the like to generate decomposition products such asphosgene, carbon dioxide, and carbon tetrachloride; as a result, itexists in the form of a composition mixed with these decompositionproducts. In particular, the present inventors have discovered that if atriphosgene composition containing decomposition products in a certainamount or more is used to prepare a diisocyanate composition, the colorand haze may be deteriorated, and it may have an impact on the stria,transmittance, yellow index, and refractive index of the final opticallens.

In addition, the present inventors have focused that triphosgene reactswith moisture in the air during storage to generate phosgene, which inturn reacts with moisture in the air to increase the b* value accordingto the CIE color coordinate. In particular, the present inventors havediscovered that if a triphosgene composition having a b* value of acertain level or more is used to prepare a diisocyanate composition, thecolor and haze may be deteriorated, and it may have an impact on thestria, transmittance, yellow index, and refractive index of the finaloptical lens. In addition, if distillation is carried out several timesin order to make a discolored diisocyanate composition colorless andtransparent, it may cause a loss in yield, thereby decreasing theeconomic efficiency.

In addition, the present inventors have focused that when water iscontained in triphosgene used in the phosgenation reaction for thepreparation of a diisocyanate, side reactions take place, therebyreducing the number of equivalents for the reaction, and it also reactswith a diisocyanate to form urea, which significantly reduces the yieldand purity of the final product. In particular, the present inventorshave discovered that it is possible to effectively control the contentof water if triphosgene is washed with a solvent having a certain rangeof polarity index and boiling point without a nucleophilic group.

Accordingly, an object of the embodiments is to provide processes forpreparing a diisocyanate composition and an optical lens capable ofenhancing the optical characteristics by controlling the content of adecomposition product in a triphosgene composition, the b* valueaccording to CIE color coordinate of the triphosgene composition in anorganic solvent, or the content of water in the triphosgene.

Solution to the Problem

According to an embodiment, there is provided a process for preparing adiisocyanate composition, which comprises reacting a diaminehydrochloride composition with a triphosgene composition to obtain adiisocyanate composition, wherein the content of a decomposition productof triphosgene in the triphosgene composition is less than 1% by weight.

According to another embodiment, there is provided a process forpreparing a diisocyanate composition, which comprises reacting a diaminehydrochloride composition with a triphosgene composition to obtain adiisocyanate composition, wherein the triphosgene composition has a b*value according to the CIE color coordinate of 1.2 or less whendissolved in orthodichlorobenzene at a concentration of 8% by weight.

According to still another embodiment, there is provided a process forpreparing a diisocyanate composition, which comprises reacting a diaminewith an aqueous hydrochloric acid solution to obtain a diaminehydrochloride composition; and reacting the diamine hydrochloridecomposition with triphosgene to obtain a diisocyanate composition,wherein the content of water in the triphosgene is 200 ppm or less.

Advantageous Effects of the Invention

In the process for preparing a diisocyanate according to the aboveembodiment, phosgene gas, which is highly toxic and has difficulties instorage and management, is not used. Instead, triphosgene, which is lesstoxic and does not require a separate cooling storage apparatus since itis solid at room temperature, is used; thus, it is excellent in thehandling convenience and processability. In particular, according to theabove embodiment, it is possible to enhance the color and haze of adiisocyanate composition and to enhance the stria, transmittance, yellowindex, and refractive index of the final optical lens by controlling thecontent of a decomposition product in a triphosgene composition, the b*value according to CIE color coordinate of the triphosgene compositionin an organic solvent, or the content of water in the triphosgene.

In addition, in the process for preparing a diisocyanate according tothe more preferable embodiment, an aqueous hydrochloric acid solution,without the use of hydrogen chloride gas, is used to prepare a diaminehydrochloride as an intermediate. Since the reaction can be carried outeven at atmospheric pressure, an additional apparatus forhigh-temperature heating and cooling is not required, and the yield canbe further enhanced.

Accordingly, the process for preparing a diisocyanate compositionaccording to the embodiment can be applied to the preparation of aplastic optical lens of high quality.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A and FIG. 1B schematically show the process for preparing adiisocyanate composition according to an embodiment.

FIG. 2 shows an example of the process equipment for the reaction of adiamine hydrochloride and triphosgene.

REFERENCE NUMERALS OF THE DRAWINGS

-   -   T-1: first tank, T-2: second tank, T-3: third tank    -   R-1: reactor, D-1: first distiller, D-2: second distiller    -   C-1: first condenser, C-2: second condenser, C-3: third        condenser    -   S-1: first scrubber, S-2: second scrubber    -   G-1: viewing window, V-1: solvent recovery apparatus.

BEST MODE FOR CARRYING OUT THE INVENTION

Throughout the present specification, when a part is referred to as“comprising” an element, it is understood that other elements may becomprised, rather than other elements are excluded, unless specificallystated otherwise.

In addition, all numbers and expression related to the physicalproperties, contents, dimensions, and the like used herein are to beunderstood as being modified by the term “about,” unless otherwiseindicated.

In the present specification, an “amine” refers to a compound having oneor more amine groups at the terminal, and a “diamine” refers to acompound having two amine groups at the terminal. They may have a widevariety of structures depending on the skeleton of an aliphatic chain,an aliphatic ring, and an aromatic ring. Specific examples of thediamine include xylylenediamine (XDA), hexamethylenediamine (HDA),2,2-dimethylpentanediamine,2,2,4-trimethylhexanediamine,butenediamine,1,3-butadiene-1,4-diamine,2,4,4-trimethylhexamethylenediamine, bis(aminoethyl)carbonate,4,4′-methylenediamine (MDA), bis(aminoethyl) ether,bis(aminoethyl)benzene, bis(aminopropyl)benzene,α,α,α′,α′-tetramethylxylylenediamine, bis(aminobutyl)benzene,bis(aminomethyl)naphthalene, bis(aminomethyl)diphenyl ether,bis(aminoethyl)phthalate, 2,6-di(aminomethyl)furan, hydrogenatedxylylenediamine (H6XDA), dicyclohexylmethanediamine, cyclohexanediamine,methylcyclohexanediamine, isophoronediamine (IPDA),dicyclohexyldimethylmethanediamine,2,2-dimethyldicyclohexylmethanediamine,2,5-bis(aminomethyl)bicyclo-[2,2,1]-heptane,2,6-bis(aminomethyl)bicyclo-[2,2,1]-heptane,3,8-bis(aminomethyl)tricyclodecane, 3,9-bis(aminomethyl)tricyclodecane,4,8-bis(aminomethyl)tricyclodecane, 4,9-bis(aminomethyl)tricyclodecane,norbomenediamine (NBDA), bis(aminomethyl) sulfide, bis(aminoethyl)sulfide, bis(aminopropyl) sulfide, bis(aminohexyl) sulfide,bis(aminomethyl) sulfone, bis(aminomethyl) disulfide, bis(aminoethyl)disulfide, bis(aminopropyl) disulfide, bis(aminomethylthio)methane,bis(aminoethylthio)methane, bis(aminoethylthio)ethane, andbis(aminomethylthio)ethane. More specifically, the diamine may be atleast one selected from the group consisting of xylylenediamine (XDA),norbornenediamine (NBDA), hydrogenated xylylenediamine (H6XDA),isophoronediamine (IPDA), and hexamethylenediamine (HDA). Thexylylenediamine (XDA) includes orthoxylylenediamine (o-XDA),metaxylylenediamine (m-XDA), and paraxylylenediamine (p-XDA).

In the present specification, an “isocyanate” refers to a compoundhaving an NCO group, a “diisocyanate” refers to a compound having twoNCO groups at the terminal. They may have a wide variety of structuresdepending on the skeleton of an aliphatic chain, an aliphatic ring, andan aromatic ring. Specific examples of the diamine include xylylenediisocyanate (XDI), hexamethylene diisocyanate (HDI),2,5-bis(isocyanatomethyl)-bicyclo[2.2.1]heptane,2,6-bis(isocyanatomethyl)-bicyclo[2.2.1]heptane, hydrogenated xylylenediisocyanate (H6XDI), dicyclohexylmethane diisocyanate, isophoronediisocyanate (IPDI), 1,2-diisocyanatobenzene, 1,3-diisocyanatobenzene,1,4-diisocyanatobenzene, 2,4-diisocyanatotoluene, ethylphenylenediisocyanate, dimethylphenylene diisocyanate, biphenyl diisocyanate,toluidine diisocyanate, 4,4′-methylenebis(phenylisocyanate) (MDI),1,2-bis(isocyanatomethyl)benzene, 1,3-bis(isocyanatomethyl)benzene,1,4-bis(isocyanatomethyl)benzene, 1,2-bis(isocyanatoethyl)benzene,1,3-bis(isocyanatoethyl)benzene, 1,4-bis(isocyanatoethyl)benzene,α,α,α′,α′-tetramethylxylylene diisocyanate,bis(isocyanatomethyl)naphthalene, bis(isocyanatomethylphenyl) ether,norbornene diisocyanate (NBDI), bis(isocyanatomethyl) sulfide,bis(isocyanatoethyl) sulfide, bis(isocyanatopropyl) sulfide,2,5-diisocyanatotetrahydrothiophene,2,5-diisocyanatomethyltetrahydrothiophene,3,4-diisocyanatomethyltetrahydrothiophene,2,5-diisocyanato-1,4-dithiane, and 2,5-diisocyanatomethyl-1,4-dithiane.More specifically, the diisocyanate may be at least one selected fromthe group consisting of xylylene diisocyanate (XDI), norbornenediisocyanate (NBDI), hydrogenated xylylene diisocyanate (H6XDI),isophorone diisocyanate (IPDI), and hexamethylene diisocyanate (HDI).The xylylene diisocyanate (XDI) includes orthoxylylene diisocyanate(o-XDI), metaxylylene diisocyanate (m-XDI), and paraxylylenediisocyanate(p-XDIA).

In the present specification, as is well known, a “composition” mayrefer to a form in which two or more chemical components are mixed orcombined in a solid, liquid, and/or gas phase while generallymaintaining their respective unique properties.

The compounds used in each reaction step according to the aboveembodiment (e.g., triphosgene) or the compounds obtained as a result ofthe reaction (e.g., diamine hydrochloride, diisocyanate) are generallypresent in a mixed or combined state with heterogeneous componentsgenerated as unreacted raw materials in each reaction step, as sidereactions or reaction with water, or as natural decomposition of thecompounds. A trace amount of these components may remain to exist withthe main components.

According to the embodiment, since attention is paid to theseheterogeneous components mixed or combined with the main compounds, evena trace amount of the heterogeneous components is treated as acomposition mixed or combined with the main compounds to specificallyillustrate the components and contents thereof.

In addition, in the present specification, for clear and easydistinction between various compositions, terms are also described incombination with the names of the main components in the composition.For example, a “diamine hydrochloride composition” refers to acomposition comprising a diamine hydrochloride as a main component, a“triphosgene composition” refers to a composition comprising triphosgeneas a main component, and a “diisocyanate composition” refers to acomposition comprising a diisocyanate as a main component. In suchevent, the content of the main component in the composition may be 50%by weight or more, 80% by weight or more, or 90% by weight or more, forexample, 90% by weight to 99.9% by weight.

In this specification, the unit of ppm refers to ppm by weight.

[Process for Preparing a Diisocyanate Composition]

The process for preparing a diisocyanate composition according to anembodiment comprises reacting a diamine hydrochloride composition with atriphosgene composition to obtain a diisocyanate composition, whereinthe content of a decomposition product of triphosgene in the triphosgenecomposition is less than 1% by weight.

The process for preparing a diisocyanate composition according toanother embodiment comprises reacting a diamine hydrochloridecomposition with a triphosgene composition to obtain a diisocyanatecomposition, wherein the triphosgene composition has a b* valueaccording to the CIE color coordinate of 1.2 or less when dissolved inorthodichlorobenzene at a concentration of 8% by weight.

The diamine hydrochloride composition may be obtained by reacting adiamine with an aqueous hydrochloric acid solution. Specifically, theprocess for preparing a diisocyanate composition according to theembodiment further comprises reacting a diamine with an aqueoushydrochloric acid solution to obtain a diamine hydrochloridecomposition.

The process for preparing a diisocyanate composition according to stillanother embodiment comprises reacting a diamine with an aqueoushydrochloric acid solution to obtain a diamine hydrochloridecomposition; and reacting the diamine hydrochloride composition withtriphosgene to obtain a diisocyanate composition, wherein the content ofwater in the triphosgene is 200 ppm or less.

FIG. 1A and FIG. 1B schematically show the process for preparing adiisocyanate composition according to an embodiment. In FIG. 1A and FIG.1B, R comprises an aromatic ring, an aliphatic ring, an aliphatic chain,and the like. As a specific example, R may be xylylene, norbornene,hydrogenated xylylene, isophorone, or hexamethylene, but it is notlimited thereto.

In FIG. 1A, (i) may comprise a step of adding an aqueous hydrochloricacid solution to react a diamine with the aqueous hydrochloric acidsolution. In FIG. 1A, (ii) may comprise at least one step selected froma precipitation step, a filtration step, a drying step, and a washingstep. In FIG. 1B, (iii) may comprise a step of adding triphosgene toreact a diamine hydrochloride composition with triphosgene. In FIG. 1B,(iv) may comprise at least one step selected from a degassing step, afiltration step, and a distillation step.

Hereinafter, each step will be described in detail.

Preparation of a Diamine Hydrochloride Composition

First, a diamine is reacted with an aqueous hydrochloric acid solutionto obtain a diamine hydrochloride composition.

In addition, after the reaction of the diamine composition and theaqueous hydrochloric acid solution, a first organic solvent may befurther introduced to obtain the diamine hydrochloride composition in asolid phase.

The following Reaction Scheme 1 shows an example of the reaction in thisstep.

In the above scheme, R comprises an aromatic ring, an aliphatic ring, analiphatic chain, and the like. As a specific example, R may be xylylene,norbornene, hydrogenated xylylene, isophorone, or hexamethylene, but itis not limited thereto.

In the conventional method in which hydrogen chloride gas is used, ahydrochloride is produced as fine particles upon the reaction atatmospheric pressure, so that the agitation inside the reactor is notsmoothly carried out. Thus, an additional process of raising thepressure to increase the internal temperature of the reactor isrequired, and there is a problem that the yield of the final product islow as well.

According to the above embodiment, however, since an aqueoushydrochloric acid solution is used, it is possible to solve the probleminvolved in the prior art in which hydrogen chloride gas is used.Specifically, when an aqueous hydrochloric acid solution is used, theproduct obtained through the reaction is in a solid form rather than aslurry form, so that the yield is high. The reaction can be carried outeven at atmospheric pressure, so that a separate apparatus or processfor rapid cooling is not required.

The concentration of the aqueous hydrochloric acid solution may be 5% byweight to 50% by weight. Within the above concentration range, it ispossible to minimize the dissolution of the hydrochloride in the aqueoushydrochloric acid solution, thereby enhancing the final yield, and toimprove the handling convenience.

Specifically, the concentration of the aqueous hydrochloric acidsolution may be 10% by weight to 45% by weight, 20% by weight to 45% byweight, or 30% by weight to 40% by weight. More specifically, theaqueous hydrochloric acid solution may have a concentration of 20% byweight to 45% by weight.

The diamine and the aqueous hydrochloric acid solution may be introducedto the reaction at an equivalent ratio of 1:2 to 5. If the equivalentratio is within the above range, it is possible to reduce the unreactedmaterials and to prevent a decrease in the yield caused by dissolutionas water is generated. Specifically, the diamine and the aqueoushydrochloric acid solution may be introduced to the reaction at anequivalent ratio of 1:2 to 2.5.

The introduction of the diamine and the aqueous hydrochloric acidsolution may be carried out while the internal temperature of thereactor is maintained to be constant. When the diamine and thehydrochloric acid aqueous solution are introduced, the internaltemperature of the reactor may be in the range of 20° C. to 100° C.Within the above temperature range, it is possible to prevent thetemperature from being raised above the boiling point, which is notsuitable for the reaction, or the temperature from being lowered toomuch, whereby the reaction efficiency is reduced.

Specifically, when the diamine and the hydrochloric acid aqueoussolution are introduced, the internal temperature of the reactor may be20° C. to 60° C. or 20° C. to 40° C. More specifically, the diamine andthe aqueous hydrochloric acid solution may be introduced to the reactionat an equivalent ratio of 1:2 to 5 at a temperature of 20° C. to 40° C.

In the conventional hydrochloride method, a large amount of heat isgenerated in the reaction, which requires rapid cooling through aseparate cooler, whereas the reaction materials are introduced while alow temperature is maintained according to the above embodiment, whichdoes not require a separate cooler.

The introduction of the diamine and the aqueous hydrochloric acidsolution may be carried out, for example, in a sequence in which thehydrochloric acid aqueous solution may be first introduced to thereactor and the diamine may then be slowly introduced to the reactor.The introduction of the diamine and/or the aqueous hydrochloric acidsolution may be carried out for 30 minutes to 1 hour.

When the introduction of the diamine and the hydrochloric acid aqueoussolution is completed, the internal temperature of the reactor may belowered to 0° C. to 20° C., 0° C. to 10° C., or 10° C. to 20° C.

The reaction between the diamine and the aqueous hydrochloric acidsolution may be carried out at atmospheric pressure for, for example, 30minutes to 2 hours with stirring.

As a result of the reaction between the diamine and the aqueoushydrochloric acid solution, a diamine hydrochloride composition in anaqueous solution form may be obtained as the reaction resultant.

Thereafter, a step of treating the diamine hydrochloride composition maybe further carried out. For example, the step of treating the diaminehydrochloride composition may comprise at least one of precipitating thediamine hydrochloride composition, filtering the diamine hydrochloridecomposition, drying the diamine hydrochloride composition, and washingthe diamine hydrochloride composition.

Specifically, a first organic solvent may be introduced to the reactionresultant to precipitate a solid diamine hydrochloride composition. Thatis, the first organic solvent may induce the precipitation of a soliddiamine hydrochloride composition through crystallization. Morespecifically, the first organic solvent may be introduced to thereaction resultant, which is cooled and further stirred to carry out thereaction.

Specifically, the first organic solvent may be at least one selectedfrom the group consisting of diethyl ether, diisopropyl ether, dioxane,tetrahydrofuran, methanol, ethanol, dimethyl sulfoxide,dimethylformamide, acetonitrile, acetone, trichloroethylene,tetrachloroethane, trichloroethanol, n-butanol, isobutanol, methyl ethylketone, methyl butyl ketone, isopropanol, hexane, chloroform, and methylacetate.

The amount (weight) of the first organic solvent introduced may be 1 to5 times the weight of the diamine. If the introduced amount is withinthe above range, it is possible to prevent the use of excessive organicsolvents while the yield of the final hydrochloride is high.Specifically, the first organic solvent may be introduced to thereaction in an amount of 1 to 2 times, 1 to 1.5 times, or 1.3 to 1.5times, the weight of the diamine.

After the first organic solvent is introduced, the cooling temperaturemay be −10° C. to 10° C. or −5° C. to 5° C. In addition, the additionalreaction time after cooling may be 30 minutes to 2 hours or 30 minutesto 1 hour.

According to a specific example, the steps of (1a) introducing theaqueous hydrochloric acid solution to a first reactor; (1b) introducingthe diamine to the first reactor and stirring them; and (1c) introducingthe first organic solvent to the first reactor and stirring them may besequentially carried out.

More specifically, the process may further comprise cooling the insideof the reactor to a temperature of 0° C. to 10° C. after theintroduction of the diamine and before stirring in step (1 b); andcooling the inside of the reactor to a temperature of −5° C. to 5° C.after the introduction of the first organic solvent and before stirringin step (1c).

After the first organic solvent is introduced, separation, filtration,washing, and drying may be further carried out. For example, after thefirst organic solvent is introduced, the aqueous layer may be separated,filtered, washed, and dried to obtain a solid diamine hydrochloridecomposition. The washing may be carried out one or more times using, forexample, a solvent having a polarity index of 5.7 or less. In addition,the drying may be carried out using vacuum drying. For example, it maybe carried out at a temperature of 40° C. to 90° C. and a pressure of2.0 torr or less.

As a result, the impurities generated in the step of obtaining thediamine hydrochloride composition may be removed together with the firstorganic solvent. Thus, the process may further comprise removing theimpurities generated in the step of obtaining the diamine hydrochloridecomposition together with the first organic solvent. Impurities aregenerated in the reaction for preparing the diamine hydrochloridecomposition and are contained in the first organic solvent. Suchimpurities may be removed by the step of removing the first organicsolvent, whereby the purity of the product may be increased.

According to the above process, a diamine is reacted with an aqueoushydrochloric acid solution, which is then subjected to additionaltreatment such as precipitation, filtration, drying, and washing,whereby a solid diamine hydrochloride composition can be obtained withhigh purity. In contrast, in the conventional process in which a diamineis reacted with hydrogen chloride gas in an organic solvent, a slurry ofa diamine hydrochloride is obtained, which is not readily purified.

The yield of the diamine hydrochloride composition thus obtained may be50% or more, 65% or more, 80% or more, 85% or more, or 90% or more,specifically 85% to 95% or 88% to 92%.

Meanwhile, the organic layer can be separated from the reactant andrecycled as an organic solvent. Thus, the recovery rate of the firstorganic solvent may be 80% or more, 85% or more, or 90% or more,specifically 80% to 95% or 80% to 82%.

Diamine Hydrochloride Composition

In the process for preparing a diamine hydrochloride as described above,the diamine is easily deteriorated by temperature and humidity due toits high reactivity and pH, so that the b* value according to the CIEcolor coordinate of the diamine hydrochloride composition may beincreased. In particular, if a diamine hydrochloride composition havinga b* value of a certain level or more is used to prepare a diisocyanatecomposition, the color and haze may be deteriorated, and it may have animpact on the stria, transmittance, yellow index, and refractive indexof the final optical lens. In addition, if distillation is carried outseveral times in order to make a discolored diisocyanate compositioncolorless and transparent, it may cause a loss in yield, therebydecreasing the economic efficiency.

According to the above embodiment, however, the b* value according tothe CIE color coordinate of the diamine hydrochloride composition inwater may be adjusted, so that it is possible to enhance the opticalcharacteristics of a diisocyanate composition and an optical lens.

The diamine hydrochloride composition prepared by the process accordingto the above embodiment has a b* value according to the CIE colorcoordinate of 1.2 or less when dissolved in water at a concentration of8% by weight. For example, the b* value according to the CIE colorcoordinate may be 1.0 or less or 0.8 or less. Specifically, the b* valueaccording to the CIE color coordinate may be 0.1 to 1.2, 0.1 to 1.0, 0.1to 0.8, or 0.3 to 1.0.

In order to adjust the b* value of the diamine hydrochloridecomposition, an aqueous hydrochloric acid solution having a content ofFe ions at a certain level or less may be used as a raw material. Forexample, the content of Fe ions in the aqueous hydrochloric acidsolution used for preparing the diamine hydrochloride composition may be0.5 ppm or less. Specifically, the content of Fe ions in the aqueoushydrochloric acid solution may be 0.3 ppm or less or 0.2 ppm or less.More specifically, the content of Fe ions in the aqueous hydrochloricacid solution may be 0.001 ppm to 0.5 ppm or 0.1 ppm to 0.3 ppm.

Alternatively, the b* value according to the CIE color coordinate of thediamine hydrochloride composition may be adjusted by washing it with asolvent having a polarity index of 9.8 or less. That is, the process forpreparing a diamine hydrochloride composition adopted in the aboveembodiment comprises washing the composition comprising a diaminehydrochloride with a solvent having a polarity index of 9.8 or less toadjust the b* value according to the CIE color coordinate to 1.2 or lesswhen dissolved in water at a concentration of 8% by weight.

In such event, the solvent having a polarity index of 9.8 or less maycomprise dichloromethane, and other solvents may be used. In addition,the temperature of the solvent having a polarity index of 9.8 or lessmay be 0° C. to 5° C.

The diamine hydrochloride composition obtained by the above processmainly comprises a diamine hydrochloride, and the content of the diaminehydrochloride may be 90% by weight to 99.9% by weight based on the totalweight of the composition. In such event, the diamine hydrochloride maycontain two of HCl bonded to the two terminal amine groups of thediamine.

In addition, the diamine hydrochloride composition may comprise Fe ions,and the content of Fe ions may be 10 ppm or less based on the totalweight of the diamine hydrochloride composition.

In addition, the content of water in the diamine hydrochloridecomposition thus obtained may be 5% or less. If it exceeds 5%, thephysical properties of the lens finally prepared are not good.

In addition, the content of water in the diamine hydrochloridecomposition obtained in the previous step may be adjusted, and it isthen introduced to the subsequent reaction. For example, the process mayfurther comprise adjusting the content of water in the diaminehydrochloride composition obtained in the previous step to 700 ppm orless.

The content of water in the diamine hydrochloride composition may beadjusted to, for example, 500 ppm or less, 300 ppm or less, 200 ppm orless, 100 ppm or less, or 50 ppm or less. Specifically, the diaminehydrochloride composition in which the content of water has beenadjusted may have a content of water of 100 ppm or less or 50 ppm orless.

The content of water in the diamine hydrochloride composition may beadjusted in advance before it is introduced to the subsequent reaction.That is, the process may further comprise measuring the content of waterin the diamine hydrochloride composition before it is introduced to thesubsequent reaction.

The content of water in the diamine hydrochloride composition may beadjusted is through at least one of washing and drying.

As an example, the content of water in the diamine hydrochloridecomposition may be adjusted by washing it with a solvent having apolarity index of 3.9 to 5.7. If the solvent used for washing asdescribed above has a polarity index of 3.9 or more, it is miscible withwater and effective in removing water. In addition, if it has a polarityindex of 5.7 or less, it does not dissolve triphosgene, therebyincreasing the yield.

In addition, if the solvent used for washing has a boiling point of 85°C. or lower, it reduces the residual solvents after drying, therebyenhancing the purity and yield of the product. For example, the boilingpoint of the solvent used for washing may be 30° C. to 85° C.

Specifically, the solvent used for washing may include at least oneselected from the group consisting of tetrahydrofuran (THF), ethylacetate, methyl acetate, methyl ethyl ketone, and acetone. Morespecifically, the solvent used for washing may include at least oneselected from tetrahydrofuran and acetone.

The content of water in the diamine hydrochloride composition may beadjusted by drying it under a reduced pressure. For example, the contentof water in the diamine hydrochloride composition may be adjusted bydrying under the conditions of a temperature of 40° C. to 90° C. and apressure of 0.01 torr to 100 torr.

The drying step may be performed after the above washing is firstperformed. That is, the content of water in the diamine hydrochloridecomposition, after the washing, may be further adjusted by drying underthe conditions of a temperature of 40° C. to 90° C. and a pressure of0.01 torr to 100 torr.

In the diamine hydrochloride composition, after the drying, the contentof the residual solvents used in the washing may be less than 500 ppm orless than 300 ppm, specifically less than 100 ppm.

Preparation of a Diisocyanate Composition

Next, the diamine hydrochloride composition is reacted with atriphosgene composition to obtain a diisocyanate composition. Thereaction of the diamine hydrochloride composition with a triphosgenecomposition may be carried out in a second organic solvent.

The following Reaction Scheme 2 shows an example of the reaction in thisstep.

In the above scheme, R comprises an aromatic ring, an aliphatic ring, analiphatic chain, and the like. As a specific example, R may be xylylene,norbornene, hydrogenated xylylene, isophorone, or hexamethylene, but itis not limited thereto.

Specifically, the diamine hydrochloride composition prepared above isintroduced to a second organic solvent, reacted with a triphosgene(BTMC, bis(trichloromethyl)carbonate) composition, and then filtered anddistilled to obtain a diisocyanate composition.

Specifically, the second organic solvent may be at least one selectedfrom the group consisting of benzene, toluene, ethylbenzene,chlorobenzene, monochlorobenzene, 1,2-dichlorobenzene, dichloromethane,1-chloro-n-butane, 1-chloro-n-pentane, 1-chloro-n-hexane, chloroform,carbon tetrachloride, n-pentane, n-hexane, n-heptane, n-octane,cyclohexane, cyclopentane, cyclooctane, and methylcyclohexane.

The amount (weight) of the second organic solvent introduced may be 1 to5 times the weight of the diamine hydrochloride composition. If theintroduced amount is within the above range, it is possible to preventthe use of excessive organic solvents while the yield of the finaldiisocyanate is high. Specifically, the second organic solvent may beintroduced to the reaction in an amount of 2 to 5 times, or 3 to 5times, the weight of the diamine hydrochloride composition.

The reaction temperature of the diamine hydrochloride composition andthe triphosgene composition is 115° C. or higher, so that the reactionbetween the diamine hydrochloride and the triphosgene composition iscarried out more smoothly, which may be advantageous for increasing theyield and shortening the reaction time. In addition, if the reactiontemperature of the diamine hydrochloride composition and the triphosgenecomposition is 160° C. or less, it is possible to suppress thegeneration of impurities such as tar when the final diisocyanate isproduced. For example, the reaction temperature of the diaminehydrochloride composition and the triphosgene composition may be 115° C.to 160° C., 15° C. to 130° C., or 130° C. to 160° C.

In addition, if the reaction temperature of the diamine hydrochloridecomposition and the triphosgene composition is 130° C. or lower, it maybe more advantageous for suppressing impurities containing chlorine(e.g., chloromethylbenzyl isocyanate, 1,3-bis(chloromethyl)benzene, andthe like). Specifically, the reaction temperature of the diaminehydrochloride composition and the triphosgene composition may be 115° C.to 130° C. More specifically, the reaction temperature of the diaminehydrochloride composition and the triphosgene composition may be 115° C.to 120° C.

The reaction of the diamine hydrochloride composition with thetriphosgene composition may be carried out for 5 hours to 100 hours. Ifthe reaction time is within the above range, the reaction time is notexcessive, and the production of unreacted materials due to thegeneration of phosgene can be minimized. Specifically, the reaction ofthe diamine hydrochloride composition with the triphosgene compositionmay be carried out for 15 hours to 40 hours, 20 hours to 35 hours, or 24hours to 30 hours.

As a specific example, the reaction of the diamine hydrochloridecomposition with the triphosgene composition may be carried out at atemperature of 115° C. to 160° C. for 5 hours to 100 hours.

The diamine hydrochloride composition and the triphosgene compositionmay be introduced to the reaction at an equivalent ratio of 1:1 to 5.When the equivalent ratio is within the above range, the reactionefficiency is high, and it is possible to prevent an increase in thereaction time due to an excessive introduction. Specifically, thediamine hydrochloride composition and the triphosgene composition may beintroduced to the reaction at an equivalent ratio of 1:1.5 to 4 or 1:2to 2.5.

The reaction of the diamine hydrochloride composition and thetriphosgene composition may sequentially comprise mixing the diaminehydrochloride composition with the second organic solvent to obtain afirst solution; mixing the triphosgene composition with the secondorganic solvent to obtain a second solution; and introducing the secondsolution to the first solution and stirring them. In such event, theintroduction of the second solution and stirring may be carried out at atemperature of 115° C. to 160° C. In addition, the introduction of thesecond solution may be divided into two or more times for a total of 25hours to 40 hours. In addition, here, the time for each introduction maybe 5 hours to 25 hours or 10 hours to 14 hours. In addition, the timefor further reaction by stirring after the introduction may be 2 hoursto 5 hours or 3 hours to 4 hours.

Alternatively, the reaction of the diamine hydrochloride composition andthe triphosgene composition may sequentially comprise (2a) introducingthe second organic solvent to a second reactor; (2b) further introducingthe diamine hydrochloride composition to the second reactor and stirringthem; and (2c) further introducing the triphosgene composition to thesecond reactor and stirring them. In such event, the introduction of thetriphosgene composition in step (2c) may be carried out by introducing asolution in which the triphosgene composition is dissolved in the samesolvent as the second organic solvent to the reactor as divided into twoor more times at a temperature of 115° C. to 160° C. for a total of 25hours to 40 hours. In such event, the time for each introduction of thetriphosgene composition may be 5 hours to 25 hours or 10 hours to 14hours. In addition, the time for further reaction by stirring after theintroduction of the triphosgene composition may be 2 hours to 5 hours or3 hours to 4 hours.

Upon the reaction, the reaction resultant may be cooled at 90° C. to110° C.

The resultant obtained through the reaction may be further subjected toseparation, degassing, cooling, filtration, distillation, and the like.

For example, after the reaction, the reaction resultant may be subjectedto degassing at 80° C. to 150° C. with the bubbling of nitrogen gas. Inaddition, after the degassing, it may be cooled to 10° C. to 30° C., andsolids may be filtered off.

The diisocyanate composition may be obtained by distillation after thereaction of the diamine hydrochloride composition and the triphosgenecomposition.

The distillation may comprise distillation to remove the second organicsolvent. For example, after the reaction, the reaction resultant may bedistilled at 40° C. to 60° C. for 2 hours to 8 hours to remove thesecond organic solvent. The pressure during the distillation may be 2.0torr or less, 1.0 torr or less, 0.5 torr or less, or 0.1 torr or less.In addition, the second organic solvent may be recovered and recycledthrough the distillation.

In addition, the distillation may comprise distilling the diisocyanate.For example, the distillation may comprise distillation of adiisocyanate at 80° C. to 160° C., specifically 100° C. to 130° C. Ifthe distillation temperature is within the above range, it is moreadvantageous for preventing a deterioration in the physical propertiesof the final optical lens such as stria, cloudiness, and yellowing byeffectively removing hydrolyzable chlorine compounds generated at hightemperatures such as chloromethylbenzyl isocyanate (CBI) and1,3-bis(chloromethyl)benzene. Specifically, the distillation may becarried out by setting the bottom temperature of the distiller to 100°C. to 130° C. For example, the distillation may be carried out bysetting the reboiler temperature to 100° C. to 130° C.

In addition, the pressure during the distillation may be 2.0 torr orless, 1.0 torr or less, 0.5 torr or less, or 0.1 torr or less.Specifically, the distillation may comprise distillation of adiisocyanate at a temperature of 100° C. to 130° C. and a pressure of 2torr or less.

In addition, the time for distillation of a diisocyanate may be 1 houror longer, 2 hours or longer, or 3 hours or longer, and may be 10 hoursor shorter or 5 hours or shorter. Specifically, the distillation of adiisocyanate may be carried out for 2 hours to 10 hours.

As a specific example, the diisocyanate composition may be obtained as aresult of subjecting the resultant of the reaction of the diaminehydrochloride composition and the triphosgene composition to firstdistillation at 40° C. to 60° C. for 2 to 8 hours and seconddistillation at 80° C. to 160° C. for 2 to 10 hours.

The yield of the distillation of a diisocyanate may be 80% or more,specifically 85% or more, or 90% or more. In such event, thedistillation yield may be calculated by measuring the amount of thediisocyanate composition upon the distillation relative to thetheoretical amount of the diisocyanate composition produced from theamounts of the diamine hydrochloride composition introduced to thereaction with the triphosgene composition.

According to the process of the above embodiment, the reactiontemperature range of the diamine hydrochloride composition and thetriphosgene composition is controlled, whereby the crude diisocyanatecomposition before purification may contain very little impurities.Specifically, the diisocyanate composition may contain 99.0% by weightor more of the diisocyanate before the distillation of a diisocyanate.In addition, the diisocyanate composition may contain 99.9% by weight ormore of the diisocyanate after the distillation of a diisocyanate.

In addition, the content of aromatic compounds having a halogen group inthe diisocyanate composition may be 1,000 ppm or less.

In addition, the yield of the diisocyanate composition finally obtainedmay be 80% or more, 85% or more, or 90% or more.

Triphosgene Composition

The triphosgene composition used in the process according to the aboveembodiment may comprise triphosgene and a decomposition product oftriphosgene.

Here, the content of the decomposition product of triphosgene in thetriphosgene composition is less than 1% by weight based on the totalweight of the triphosgene composition.

For example, the content of the decomposition product of triphosgene inthe triphosgene composition may be 0.9% by weight or less, 0.7% byweight or less, or 0.5% by weight or less. Specifically, the content ofthe decomposition product of triphosgene in the triphosgene compositionmay be 0.01% by weight to 0.9% by weight or 0.01% by weight to 0.7% byweight. More specifically, the content of the decomposition product oftriphosgene in the triphosgene composition may be 0.01% by weight to0.5% by weight.

In addition, the content of triphosgene in the triphosgene compositionis 50% by weight or more, 70% by weight or more, 80% by weight or more,or 90% by weight or more, based on the total weight of the triphosgenecomposition. For example, the content of triphosgene in the triphosgenecomposition may be 70/by weight to 99.9% by weight or 80% by weight to99.9% by weight. Specifically, the content of triphosgene in thetriphosgene composition may be 90% by weight to 99.9% by weight.

The decomposition product of triphosgene refers to a compound producedby the decomposition of triphosgene for various reasons. For example,triphosgene is in part decomposed by various causes such as air metalsalt, silica gel, dust, heat, and the like to generate phosgene, carbondioxide, and carbon tetrachloride (see the following Reaction Scheme 3).

As a result, the triphosgene composition may comprise phosgene, carbondioxide, carbon tetrachloride, and the like. In particular, if atriphosgene composition containing carbon tetrachloride in a certainamount or more is used to prepare a diisocyanate composition, the colorand haze may be deteriorated, and it may have an impact on the stria,transmittance, yellow index, and refractive index of the final opticallens.

However, according to the above embodiment, the content of adecomposition product such as carbon tetrachloride in triphosgene usedto prepare a diisocyanate composition is adjusted to less than 1% byweight, whereby it is possible to enhance the characteristics of thefinal optical lens. For example, the content of carbon tetrachloride inthe triphosgene composition may be 0.9% by weight or less, 0.7% byweight or less, or 0.5% by weight or less. Specifically, the content ofcarbon tetrachloride in the triphosgene composition may be 0.01% byweight to 0.9% by weight or 0.01% by weight to 0.7% by weight. Morespecifically, the content of carbon tetrachloride in the triphosgenecomposition may be 0.01% by weight to 0.5% by weight.

In particular, the content of the decomposition product of triphosgenein the triphosgene composition may be adjusted by washing it withdiethyl ether at 5° C. or lower. That is, the process for preparing atriphosgene composition adopted in the above embodiment compriseswashing a composition comprising triphosgene with diethyl ether at 5σCor lower to adjust the content of a decomposition product of triphosgenein the triphosgene composition to less than 1% by weight based on thetotal weight of the composition.

Alternatively, if the triphosgene composition contains less than 1% byweight of a decomposition product of triphosgene without such washing,it may be used for preparing a diisocyanate composition without anyother treatment.

In addition, the triphosgene composition used in the process accordingto the above embodiment has a b* value according to the CIE colorcoordinate of 1.2 or less when dissolved in orthodichlorobenzene at aconcentration of 8% by weight. For example, the b* value according tothe CIE color coordinate may be 1.0 or less, specifically 0.8 or less.More specifically, the b* value according to the CIE color coordinatemay be 0.1 to 1.2, 0.1 to 1.0, 0.3 to 1.2, or 0.1 to 0.8.

The b* value according to the CIE color coordinate of the triphosgenecomposition may be adjusted by washing it with a 10% to 30/sodiumchloride solution.

Triphosgene may react with moisture in the air during storage togenerate phosgene, which in turn may react with moisture in the air toincrease the b* value according to the CIE color coordinate oftriphosgene. If a triphosgene composition having a b* value of a certainlevel or more is used to prepare a diisocyanate composition, the colorand haze may be deteriorated, and it may have an impact on the stria,transmittance, yellow index, and refractive index of the final opticallens. In addition, if distillation is carried out several times in orderto make a discolored diisocyanate composition colorless and transparent,it may cause a loss in yield, thereby decreasing the economicefficiency.

According to the above embodiment, however, the b* value according tothe CIE color coordinate of the triphosgene composition in an organicsolvent may be adjusted, so that it is possible to enhance the color andhaze of a diisocyanate composition prepared using the same.

The b* value according to the CIE color coordinate of the triphosgenecomposition may be adjusted by washing it with a 10% to 30% sodiumchloride solution. That is, the process for preparing a triphosgenecomposition used in the above embodiment comprises washing thecomposition comprising triphosgene with a 10% to 30% sodium chloridesolution to adjust the b* value according to the CIE color coordinate to1.2 or less when dissolved in orthodichlorobenzene at a concentration of8% by weight.

In addition, according to the above embodiment, the content of water intriphosgene used in the reaction of the diamine hydrochloridecomposition and triphosgene is 200 ppm or less.

The content of water in the triphosgene may be adjusted in advancebefore it is introduced to the reaction. Thus, the process may furthercomprise measuring the content of water in the triphosgene before it isintroduced to the reaction.

As a result of the measurement, if the content of water in triphosgeneis 200 ppm or less, it may be introduced to the reaction as it is.However, if the content of water in the triphosgene exceeds 200 ppm, thecontent of water may be adjusted.

For example, the content of water in the triphosgene may be adjustedthrough at least one further step of washing and drying.

As an example, the triphosgene may be washed with a solvent having apolarity index of 3.9 to 5.7 before it is introduced to the reaction. Ifthe solvent used for washing as described above has a polarity index of3.9 or more, it is miscible with water and effective in removing water.In addition, if it has a polarity index of 5.7 or less, it does notdissolve triphosgene, thereby increasing the yield.

In addition, if the solvent used in the washing does not have a hydroxylgroup or an amine group, it is possible to enhance the purity and yieldof the product by preventing side reactions with triphosgene.

In addition, if the solvent used for washing has a boiling point of 85°C. or lower, it reduces the residual solvents after drying, therebyenhancing the purity and yield of the product. For example, the boilingpoint of the solvent used for washing may be 30° C. to 85° C.

Specifically, the solvent used for washing may include at least oneselected from the group consisting of tetrahydrofuran (THF), ethylacetate, methyl acetate, methyl ethyl ketone, and acetone. Morespecifically, the solvent used for washing may include at least oneselected from tetrahydrofuran and acetone.

In addition, the content of water in the triphosgene may be adjusted bydrying it under a reduced pressure. For example, the triphosgene may bedried for 2 hours to 10 hours under the conditions of a temperature of20° C. to 60° C. and a pressure of 0.01 torr to 100 torr before it isintroduced to the reaction.

The drying step may be performed after the above washing is firstperformed. That is, the triphosgene, after the washing, may be furtherdried under the conditions of a temperature of 20° C. to 60° C. and apressure of 0.01 torr to 100 torr.

In the triphosgene, after the drying, the content of the residualsolvents used in the washing may be less than 100 ppm.

In addition, the content of water in the triphosgene may be 100 ppm orless, or 50 ppm or less, after the further step (i.e., at least one ofwashing and drying).

As described above, the content of water in triphosgene is adjustedwithin a specific range, so that the formation of urea during thephosgenation reaction can be suppressed, thereby preventing adeterioration in the physical properties of the final optical lens suchas stria, cloudiness, and yellowing.

Adjustment of the Content of Water in the Second Organic Solvent

In addition, the content of water in the organic solvent (i.e., secondorganic solvent) used in the reaction of the diamine hydrochloridecomposition and triphosgene may be adjusted.

For example, the content of water in the second organic solvent used inthe reaction of the diamine hydrochloride composition and triphosgenemay be 200 ppm or less.

The content of water in the second organic solvent may be adjusted inadvance before it is introduced to the reaction. Thus, the process mayfurther comprise measuring the content of water in the second organicsolvent before it is introduced to the reaction.

As a result of the measurement, if the content of water in the secondorganic solvent is 200 ppm or less, it may be introduced to the reactionas it is. However, if the content of water in the second organic solventexceeds 200 ppm, the content of water may be adjusted.

Specifically, the content of water in the second organic solvent may beadjusted by dehydration under a reduced pressure. The pressure duringthe dehydration may be 2.0 torr or less, 1.0 torr or less, 0.5 torr orless, or 0.1 torr or less. The temperature during the dehydration is 20°C. or higher, which is advantageous for removing sufficient water. Inaddition, it is 40° C. or lower, which is advantageous for increasingthe dehydration yield by suppressing the evaporation of the solventduring the dehydration step. Thus, the temperature during thedehydration may be adjusted to 20° C. to 40° C. In addition, the timefor the dehydration may be 1 hour or longer or 2 hours or longer, and 5hours or shorter or 3 hours or shorter. As a specific example, thedehydration may be performed for 1 hour to 3 hours under a pressure of0.5 torr or less. The equipment and method used for the dehydration arenot particularly limited. For example, the dehydration may be performedwith a vacuum pump with stirring.

The dehydration yield may be 80% or more, specifically 85% or more, or90% or more.

In addition, the content of water in the second organic solvent may be100 ppm or less after the dehydration.

As described above, the content of water in the organic solvent used inthe reaction of a diamine hydrochloride composition and triphosgene isadjusted within a specific range, so that the formation of urea duringthe phosgenation reaction can be suppressed, thereby preventing adeterioration in the physical properties of the final optical lens suchas stria, cloudiness, and yellowing. In addition, the content of watercontained in the organic solvent during the reaction, transport, andstorage is reduced. Even if the organic solvent is recovered after thereaction and then recycled for the next reaction, the quality of theproduct may not be deteriorated.

Diisocyanate Composition

The diisocyanate composition prepared using a diamine hydrochloridecomposition and a triphosgene composition as described above may beimproved in terms of the color and haze.

The diisocyanate composition may have an APHA (American Public HealthAssociation) color value of 20 or less or 10 or less. Specifically, thediisocyanate composition may have an APHA color value of 1 to 20 or 1 to10.

In addition, the diisocyanate composition has a b* value according tothe CIE color coordinate of 1.5 or less or 1.2 or less. Specifically,the b* value according to the CIE color coordinate of the diisocyanatecomposition may be 1.0 or less. More specifically, the b* valueaccording to the CIE color coordinate of the diisocyanate compositionmay be 0.1 to 1.2, 0.1 to 1.0, 0.3 to 1.2, or 0.1 to 0.8.

In addition, the diisocyanate composition may have a haze of 10% orless, 5% or less, or 3% or less.

Thus, the diisocyanate thus prepared according to the embodiment can beapplied to a plastic optical lens of high quality.

In addition, the content of Fe ions in the diisocyanate composition maybe 10 ppm or less, 5 ppm or less, 2 ppm or less, or 1 ppm or less.Specifically, the content of Fe ions in the diisocyanate composition maybe 0.2 ppm or less.

In addition, the content of a diisocyanate in the diisocyanatecomposition may be 90% by weight or more, 95% by weight or more, or99.5% by weight or more, specifically 90% to 99.9% by weight.

In addition, the diisocyanate composition may further comprise benzylisocyanate, methylbenzyl isocyanate, cyanobenzyl isocyanate, and thelike. The total content of these components may be about 1% by weight orless.

The diisocyanate composition may comprise xylylene diisocyanate or otherdiisocyanates used in the preparation of optical lenses. Specifically,it may comprise at least one selected from the group consisting oforthoxylylene diisocyanate (o-XDI), metaxylylene diisocyanate (m-XDI),paraxylylene diisocyanate (p-XDI), norbornene diisocyanate (NBDI),hydrogenated xylylene diisocyanate (H6XDI), isophorone diisocyanate(IPDI), and hexamethylene diisocyanate (HDI).

According to the process of the above embodiment, the yield of adiisocyanate is high, the recycling rate of organic solvents isexcellent, it is environmentally friendly since highly toxic phosgenegas is not used, it is possible to react at atmospheric pressure, and aseparate apparatus for pressurization or rapid cooling is not required.

Measurement of the Color and Transparency of a Reaction Solution

The step of obtaining a diisocyanate composition from the diaminehydrochloride composition and the triphosgene composition may comprise(aa) reacting the diamine hydrochloride composition with triphosgene ina second organic solvent in a reactor to obtain a reaction solution;(ab) measuring the color and transparency of the reaction solution; and(ac) obtaining a diisocyanate composition from the reaction solution.

In the reaction of the diamine hydrochloride composition and thetriphosgene composition, the color and transparency of the reactionsolution may be measured to adjust the reaction conditions.

For example, in the reaction of metaxylylenediamine hydrochloride andthe triphosgene composition to obtain metaxylylene diisocyanate, thereaction solution at the beginning of the reaction may be opaquecolorless or white, and the reaction solution at the time when thereaction is ordinarily completed may be transparent or close totransparent in a light brown color.

For example, in the step of measuring the color and transparency of thereaction solution, the reaction solution may have a transparent lightbrown color.

Specifically, the reaction solution may have an L* value of 45 to 60, ana* value of 3 to 15, and a b* value of 15 to 30 in the CIE-LAB colorcoordinate. More specifically, the reaction solution may have an L*value of 50 to 55, an a* value of 5 to 10, and a b* value of 20 to 25 inthe CIE-LAB color coordinate.

In addition, the reaction solution may have a transmittance of 60% ormore, 70% or more, 80/or more, or 90% or more, for light having awavelength of 550 nm. In addition, the reaction solution may have a hazeof 20% or less, 10% or less, 5% or less, or 3% or less. Specifically,the reaction solution may have a transmittance of 70% or more for lighthaving a wavelength of 550 nm and a haze of 10% or less. Morespecifically, the reaction solution may have a transmittance of 80% ormore for light having a wavelength of 550 nm and a haze of 5% or less.

On the other hand, if the reaction of the metaxylylenediaminehydrochloride and the triphosgene composition is not completed, thereaction solution may be opaque or have a precipitate, and the color maybe pale, white, or colorless. In addition, if side reactions take placeto a significant extent, the reaction solution may be opaque or may havea color other than light brown, for example, a dark brown or dark color.

The reaction of the diamine hydrochloride composition and thetriphosgene composition may be carried out simultaneously with the stepof measuring the color and transparency of the reaction solution.

That is, while the reaction of the diamine hydrochloride composition andthe triphosgene composition is being carried out, the color andtransparency of the reaction solution may be measured in real time.

In addition, for more accurate measurement, a part of the reactionsolution may be collected to precisely measure the color andtransparency thereof. For example, the measurement of the color andtransparency of the reaction solution may be carried out by collecting apart of the reaction solution and measuring the color and transparencyof the collected reaction solution.

In such event, the reaction equivalent, reaction temperature, orreaction time may be adjusted according to the color and transparency ofthe reaction solution. For example, the timing for terminating thereaction may be determined according to the color and transparency ofthe reaction solution. Specifically, the timing for terminating thereaction may come after when the reaction solution turns a transparentlight brown color.

As an example, the reactor may have a viewing window, and themeasurement of the color and transparency of the reaction solution maybe carried out through the viewing window.

The reactor is connected to one or more stages of condensers. Once thegas generated in the reactor has been transferred to the one or morestages of condensers, the second organic solvent present in the gas maybe condensed and recycled to the reactor.

The one or more stages of condensers are connected to a first scrubberand a second scrubber. The gas transferred from the reactor to the oneor more stages of condensers contains hydrogen chloride gas and phosgenegas, the first scrubber may dissolve the hydrogen chloride gas in waterto produce an aqueous solution, and the second scrubber may neutralizethe phosgene gas with an aqueous NaOH solution.

In addition, the reactor is connected to one or more stages ofdistillers. The reaction solution is transferred to the one or morestages of distillers, and the one or more stages of distillers mayseparate the diisocyanate composition and the second organic solventfrom the reaction solution.

The separated second organic solvent may be recycled for the reaction ofthe diamine hydrochloride composition and the triphosgene composition.

FIG. 2 shows an example of the process equipment for the reaction of adiamine hydrochloride composition and a triphosgene composition.

First, a first tank (T-1) is charged with a second organic solvent and atriphosgene composition, and the temperature is maintained to beconstant by refluxing hot water. The inside of a reactor (R-1) is purgedwith nitrogen, a second organic solvent is introduced thereto withstirring, a diamine hydrochloride composition is slowly introducedthereto, and they are stirred while the internal temperature of thereactor is maintained to be constant.

Thereafter, the triphosgene composition in the second organic solvent isgradually introduced to the reactor (R-1) from the first tank (T-1). Theintroduction of the triphosgene composition in the second organicsolvent is carried out at a time or divided into two or more times. Atthat time, stirring is performed while the internal temperature of thereactor (R-1) is maintained to be constant. Upon completion of theintroduction, an additional reaction is carried out while stirring isperformed for a certain period of time. As an example, the color andtransparency of the reaction solution are monitored with the naked eyesthrough a viewing window (G-1) provided in the reactor (R-1). As anotherexample, the color and transparency of the reaction solution aremeasured with an optical device through the viewing window (G-1)provided in the reactor (R-1). The optical device may include a digitalcamera, a spectrometer, and optical analysis equipment.

The gas (second organic solvent, hydrogen chloride, phosgene, and thelike) present inside the reactor (R-1) is transferred to a firstcondenser (C-1). In the first condenser (C-1), the second organicsolvent is firstly condensed by cooling and recycled to the reactor(R-1), and the remaining gas is transferred to a second condenser (C-2).In the second condenser (C-2), the second organic solvent is secondlycondensed by cooling and recycled to the reactor (R-1), and theremaining gas is transferred to a third condenser (C-3). In the thirdcondenser (C-3), the second organic solvent is thirdly condensed bycooling and recycled to the reactor (R-1).

Once the second organic solvent is removed while it passes through themulti-stage condensers as described above, the remaining gas (hydrogenchloride, phosgene, and the like) is transferred to a first scrubber(S-1). In the first scrubber (S-1), hydrogen chloride gas is dissolvedin water to obtain an aqueous hydrochloric acid solution and stored in asecond tank (T-2), and the remaining gas is transferred to a secondscrubber (S-2). In the second scrubber (S-1), phosgene (COCl₂) gas maybe neutralized with an aqueous sodium hydroxide solution stored in athird tank (T-3) and removed.

The reaction solution obtained from the reactor (R-1) is sequentiallytransferred to a first distiller (D-1) and a second distiller (D-2).While it undergoes first and second distillation, the diisocyanatecomposition and the second organic solvent are separated from thereaction solution.

The second organic solvent separated from the reaction solution may betransferred to, and stored in, a solvent recovery apparatus (V-1).Thereafter, it may be recycled for the reaction of the diaminehydrochloride composition and the triphosgene composition.

In addition, the diisocyanate composition separated from the reactionsolution may be further subjected to filtration and drying to provide afinal product.

[Process for the Preparation of an Optical Lens]

The diisocyanate composition prepared in the above embodiment may becombined with other components to prepare a composition for an opticalmaterial. That is, the composition for an optical material comprises adiisocyanate composition prepared according to the above embodiment anda thiol or an episulfide. The composition for an optical material may beused to prepare an optical material, specifically an optical lens. Forexample, the composition for an optical material is mixed and heated andcured in a mold to produce an optical lens. The process for preparing anoptical lens or the characteristic thereof described below should beunderstood as a process for preparing various optical materials or thecharacteristic thereof that can be implemented using the diisocyanatecomposition according to the embodiment in addition to an optical lens.

The process for preparing an optical lens according to an embodimentcomprises reacting a diamine hydrochloride composition with atriphosgene composition to obtain a diisocyanate composition; and mixingthe diisocyanate composition with a thiol or an episulfide andpolymerizing and curing the resultant in a mold, wherein the content ofa decomposition product of triphosgene in the triphosgene composition isless than 1% by weight.

The process for preparing an optical lens according to anotherembodiment comprises reacting a diamine hydrochloride composition with atriphosgene composition to obtain a diisocyanate composition; and mixingthe diisocyanate composition with a thiol or an episulfide andpolymerizing and curing the resultant in a mold, wherein the triphosgenecomposition has a b* value according to the CIE color coordinate of 1.2or less when dissolved in orthodichlorobenzene at a concentration of 8%by weight.

The process for preparing an optical lens according to still anotherembodiment comprises reacting a diamine with an aqueous hydrochloricacid solution to obtain a diamine hydrochloride composition; reactingthe diamine hydrochloride composition with triphosgene to obtain adiisocyanate composition; and mixing the diisocyanate composition with athiol or an episulfide and polymerizing and curing the resultant in amold, wherein the content of water in the triphosgene is 200 ppm orless.

The thiol may be a polythiol containing two or more SH groups. It mayhave an aliphatic, alicyclic, or aromatic skeleton. The episulfide mayhave two or more thioepoxy groups. It may have an aliphatic, alicyclic,or aromatic skeleton.

Specific examples of the thiol include bis(2-mercaptoethyl) sulfide,4-mercaptomethyl-1,8-dimercapto-3,6-dithiaoctane,2,3-bis(2-mercaptoethylthio)propane-1-thiol,2,2-bis(mercaptomethyl)-1,3-propanedithiol,tetrakis(mercaptomethyl)methane,2-(2-mercaptoethylthio)propane-1,3-dithiol,2-(2,3-bis(2-mercaptoethylthio)propylthio)ethanethiol,bis(2,3-dimercaptopropanyl) sulfide, bis(2,3-dimercaptopropanyl)disulfide, 1,2-bis(2-mercaptoethylthio)-3-mercaptopropane,1,2-bis(2-(2-mercaptoethylthio)-3-mercaptopropylthio)ethane,bis(2-(2-mercaptoethylthio)-3-mercaptopropyl) sulfide,bis(2-(2-mercaptoethylthio)-3-mercaptopropyl) disulfide,2-(2-mercaptoethyIthio)-3-2-mercapto-3-[3-mercapto-2-(2-mercaptoethylthio)-propylthio]propylthio-propane-1-thiol,2,2-bis-(3-mercapto-propionyloxymethyl)-butyl ester,2-(2-mercaptoethylthio)-3-(2-(2-[3-mercapto-2-(2-mercaptoethylthio)-propylthio]ethylthio)ethylthio)propane-1-thiol,(4R,11S)-4,11-bis(mercaptomethyl)-3,6,9,12-tetrathiatetradecane-1,14-dithiol,(S)-3-((R-2,3-dimercaptopropyl)thio)propane-1,2-dithiol,(4R,14R)-4,14-bis(mercaptomethyl)-3,6,9,12,15-pentathiaheptane-1,17-dithiol,(S)-3-((R-3-mercapto-2-((2-mercaptoethyl)thio)propyl)thio)-2-((2-mercaptoethyl)thio)propane-1-thiol,3,3′-dithiobis(propane-1,2-dithiol),(7R,11S)-7,11-bis(mercaptomethyl)-3,6,9,12,15-pentathiaheptadecane-1,17-dithiol,(7R,12S)-7,12-bis(mercaptomethyl)-3,6,9,10,13,16-hexathiaoctadecane-1,18-dithiol,5,7-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane,4,7-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane,4,8-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane,pentaerythritol tetrakis(3-mercaptopropionate), trimethylolpropanetris(3-mercaptopropionate), pentaethritol tetrakis(2-mercaptoacetate),bispentaerythritol-ether-hexakis(3-mercaptopropionate),1,1,3,3-tetrakis(mercaptomethylthio)propane,1,1,2,2-tetrakis(mercaptomethylthio)ethane,4,6-bis(mercaptomethylthio)-1,3-dithiane,2-(2,2-bis(mercaptodimethylthio)ethyl)-1,3-dithiane,2,5-bismercaptomethyl-1,4-dithiane,bis(mercaptomethyl)-3,6,9-trithiaundecan-1,11-dithiol.

Preferably, the thiol may be 2-(2-mercaptoethylthio)propane-1,3-dithiol,2,3-bis(2-mercaptoethylthio)propane-1-thiol,2-(2,3-bis(2-mercaptoethylthio)propylthio)ethanethiol,1,2-bis(2-mercaptoethylthio)-3-mercaptopropane,1,2-bis(2-(2-mercaptoethylthio)-3-mercaptopropylthio)-ethane,bis(2-(2-mercaptoethylthio)-3-mercaptopropyl) sulfide,2-(2-mercaptoethylthio)-3-2-mercapto-3-[3-mercapto-2-(2-mercaptoethylthio)-propylthio]propylthio-propane-1-thiol,2,2′-thiodiethanethiol,4,14-bis(mercaptomethyl)-3,6,9,12,15-pentathiahectadecane-1,17-dithiol,2-(2-mercaptoethylthio)-3-[4-(1-{4-[3-mercapto-2-(2-mercaptoethylthio)-propoxy]-phenyl}-1-methylethyl)-phenoxy]-propane-1-thiol,pentaerythritol tetrakis(3-mercaptopropionate), pentaerythritolmercaptoacetate, trimethanolpropanetrismercaptopropionate, glyceroltrimercaptopropionate, dipentaerythritol hexamercaptopropionate, or2,5-bismercaptomethyl-1,4-dithiane.

The thiol may be any one or two or more of the exemplary compounds, butit is not limited thereto.

In addition, specific examples of the episulfide includebis(β-epithiopropylthio)methane, 1,2-bis(β-epithiopropylthio)ethane,1,3-bis(β-epithiopropylthio)propane,1,2-bis(β-epithiopropylthio)propane,1-(β-epithiopropylthio)-2-(β-epithiopropylthiomethyl)propane,1,4-bis(β-epithiopropylthio)butane,1,3-bis(β-epithiopropylthio)butane,1-(β-epithiopropylthio)-3-(β-epithiopropylthiomethyl)butane,1,5-bis(fp-epithiopropylthio)pentane,1-(β-epithiopropylthio)-4-(β-epithiopropylthiomethyl)pentane,1,6-bis(β-epithiopropylthio)hexane,1-(β-epithiopropylthio)-5-(β-epithiopropylthiomethyl)hexane,1-(β-epithiopropylthio)-2-[(2-β-epithiopropylthioethyl)thio]ethane,1-(β-epithiopropylthio)-2-[[2-(2-β-epithiopropylthioethyl)thioethyl]thio]ethane,tetrakis(β-epithiopropylthiomethyl)methane,1,1,1-tris(β-epithiopropylthiomethyl)propane,1,5-bis(β-epithiopropylthio)-2-(β-epithiopropylthiomethyl)-3-thiapentane,1,5-bis(β-epithiopropylthio)-2,4-bis(β-epithiopropylthiomethyl)-3-thiapentane,1-(β-epithiopropylthio)-2,2-bis(β-epithiopropylthiomethyl)-4-thiahexane,1,5,6-tris(β-epithiopropylthio)-4-(β-epithiopropylthiomethyl)-3-thiahexane,1,8-bis(β-epithiopropylthio)-4-(β-epithiopropylthiomethyl)-3,6-dithiaoctane,1,8-bis(β-epithiopropylthio)-4,5-bis(β-epithiopropylthiomethyl)-3,6-dithiaoctane,1,8-bis(β-epithiopropylthio)-4,4-bis(β-epithiopropylthiomethyl)-3,6-dithiaoctane,1,8-bis(β-epithiopropylthio)-2,4,5-tris(β-epithiopropylthiomethyl)-3,6-dithiaoctane,1,8-bis(β-epithiopropylthio)-2,5-bis(β-epithiopropylthiomethyl)-3,6-dithiaoctane,1,9-bis(β-epithiopropylthio)-5-(β-epithiopropylthiomethy)-5-[(2-β-epithiopropylthioethyl)thiomethyl]-3,7-ditianonane,1,10-bis(β-epithiopropylthio)-5,6-bis[(2-β-epithiopropylthioethyl)thio]-3,6,9-trithiadecane,1,11-bis(β-epithiopropylthio)-4,8-bis(β-epithiopropylthiomethyl)-3,6,9-trithiaundecane,1,11-bis(β-epithiopropylthio)-5,7-bis(β-epithiopropylthiomethyl)-3,6,9-trithiaundecane,1,11-bis(β-epithiopropylthio)-5,7-[(2-β-epithiopropylthioethyl)thiomethyl]-3,6,9-trithiaundecane,1,11-bis(β-epithiopropylthio)-4,7-bis(β-epithiopropylthiomethyl)-3,6,9-trithiaundecane,1,3-bis(β-epithiopropylthio)cyclohexane,1,4-bis(β-epithiopropylthio)cyclohexane,1,3-bis(β-epithiopropylthiomethyl)cyclohexane,1,4-bis(β-epithiopropylthiomethyl)cyclohexane,bis[4-(β-epithiopropylthio)cyclohexyl]methane,2,2-bis[4-(β-epithiopropylthio)cyclohexyl]propane,bis[4-(β-epithiopropylthio)cyclohexyl] sulfide,2,5-bis(β-epithiopropylthiomethyl)-1,4-dithiane,2,5-bis(β-epithiopropylthioethylthiomethyl)-1,4-dithiane,1,3-bis(β-epithiopropylthio)benzene,1,4-bis(β-epithiopropylthio)benzene,1,3-bis(β-epithiopropylthiomethyl)benzene,1,4-bis(β-epithiopropylthiomethyl)benzene,bis[4-(β-epithiopropylthio)phenyl]methane,2,2-bis[4-(β-epithiopropylthio)phenyl]propane,bis[4-(β-epithiopropylthio)pheny]sulfide,bis[4-(β-epithiopropylthio)phenyl] sulfone, and4,4′-bis(β-epithiopropylthio)biphenyl.

The episulfide may be any one or two or more of the exemplary compounds,but it is not limited thereto. In addition, the episulfide may be acompound in which at least one of the hydrogens of its thioepoxy groupis substituted with a methyl group.

The composition for an optical material may comprise the diisocyanatecomposition and the thiol or episulfide in a mixed state or in aseparated state. That is, in the composition, they may be in a state ofbeing compounded in contact with each other or separated from each otherso as not to contact each other.

The composition for an optical material may comprise the thiol orepisulfide and the diisocyanate composition at a weight ratio of 2:8 to8:2, 3:7 to 7:3, or 4:6 to 6:4.

A catalyst, a chain extender, a crosslinking agent, an ultravioletstabilizer, an antioxidant, an anti-coloring agent, a dye, a filler, arelease agent, and the like may be further added depending on thepurpose when the composition for an optical material and an optical lensare prepared.

The thiol or episulfide is mixed with a diisocyanate composition andother additives, which is defoamed, injected into a mold, and graduallypolymerized while the temperature is gradually elevated from low to hightemperatures. The resin is cured by heating to prepare an optical lens.

The polymerization temperature may be, for example, 20° C. to 150° C.,particularly 25° C. to 120° C. In addition, a reaction catalyst, whichis conventionally used in the production of polythiourethane, may beemployed in order to control the reaction rate. Specific examples of thereaction catalyst are as exemplified above.

In addition, if required, the optical lens thus prepared may besubjected to physical or chemical treatment such as anti-reflectioncoating, hardness, enhancements in abrasion resistance and chemicalresistance, anti-fogging, surface polishing, antistatic treatment, hardcoat treatment, anti-reflection treatment, and dyeing treatment.

The optical lens prepared by the above process has excellent opticalproperties such as transparency, refractive index, and yellow index. Forexample, the optical lens may have a refractive index of 1.55 or more,specifically a refractive index of 1.55 to 1.77. Alternatively, theoptical lens may have a refractive index of 1.6 or more, specifically arefractive index of 1.6 to 1.7.

In addition, the optical lens may have an Abbe number of 30 to 50,specifically 30 to 45 or 31 to 40. In addition, the optical lens mayhave a light transmittance of 80% or more, 85% or more, or 87% or more,which may be a total light transmittance.

In addition, the optical lens may have a yellow index (Y.I.) of 30 orless, 25 or less, or 20 or less, for example, 1 to 25 or 10 to 20.Specifically, the optical lens may have a transmittance of 85% or moreand a yellow index of 20 or less.

MODE FOR CARRYING OUT THE INVENTION

Hereinafter, more specific embodiments are illustrated, but the presentinvention is not limited thereto.

Preparation of a Diamine Hydrochloride Composition Example A1

A 5-liter, 4-neck reactor was charged with 963.5 g (9.25 moles) of anaqueous solution of 35% hydrochloric acid, followed by lowering theinternal temperature of the reactor to 15° C. with stirring. While thetemperature of the reactor was maintained at 50° C., 600.0 g (4.4 moles)of metaxylylenediamine (m-XDA) was introduced for 1 hour. Uponcompletion of the introduction, the internal temperature of the reactorwas lowered to 10° C., and it was stirred for 1 hour. Thereafter,1,200.0 g of diethyl ether (Et₂O) as an organic solvent was introduced,and the internal temperature of the reactor was lowered to −5° C.,followed by stirring for 1 hour. Upon completion of the reaction, it wassubjected to vacuum filtration using a filter, and the filtered diethylether was recovered for reuse. The recovery rate of the diethyl etherwas 73%. Upon the vacuum filtration, a metaxylylenediamine (m-XDA)hydrochloride composition was obtained. In order to remove the residualorganic solvent and water, drying was performed under the conditions ofa reactor external temperature of 90° C. and a vacuum pump of 0.1 Torrto obtain a final metaxylylenediamine (m-XDA) hydrochloride composition.The m-XDA hydrochloride composition thus obtained was in a solid form ofa pale yellow, the yield was 88%, and the water content was 2%.

Example A2

A 5-liter, 4-neck reactor was charged with 986.5 g (9.47 moles) of anaqueous solution of 35% hydrochloric acid, followed by lowering theinternal temperature of the reactor to 15° C. with stirring. While thetemperature of the reactor was maintained at 50° C., 600.0 g (4.4 moles)of m-XDA was introduced for 1 hour. Upon completion of the introduction,the internal temperature of the reactor was lowered to 10° C., and itwas stirred for 1 hour. Thereafter, 1,260 g of isopropanol (i-PrOH) asan organic solvent was introduced, and the internal temperature of thereactor was lowered to −5° C., followed by stirring for 1 hour. Uponcompletion of the reaction, it was subjected to vacuum filtration usinga filter, and the filtered isopropanol was recovered for reuse. Here,the recovery rate of the isopropanol was 75%. Upon the vacuumfiltration, a m-XDA hydrochloride composition was obtained. In order toremove the residual organic solvent and water, drying was performedunder the conditions of a reactor external temperature of 90° C. and avacuum pump of 0.1 Torr to obtain a final m-XDA hydrochloridecomposition. The m-XDA hydrochloride composition thus obtained was in asolid form of a pale yellow, the yield was 88%, and the water contentwas 2%.

Example A3

A 5-liter, 4-neck reactor was charged with 1,009.4 g (9.69 moles) of anaqueous solution of 35% hydrochloric acid, followed by lowering theinternal temperature of the reactor to 15° C. with stirring. While thetemperature of the reactor was maintained at 50° C., 600.0 g (4.4 moles)of m-XDA was introduced for 1 hour. Upon completion of the introduction,the internal temperature of the reactor was lowered to 10° C., and itwas stirred for 1 hour. Thereafter, 1,320 g of tetrahydrofuran wasintroduced, and the internal temperature of the reactor was lowered to−5° C., followed by stirring for 1 hour. Upon completion of thereaction, it was subjected to vacuum filtration using a filter, and thefiltered tetrahydrofuran was recovered for reuse. The recovery rate ofthe tetrahydrofuran was 82%. Upon the vacuum filtration, a m-XDAhydrochloride composition was obtained. In order to remove the residualsolvent and water, drying was performed under the conditions of areactor external temperature of 90° C. and a vacuum pump of 0.1 Torr toobtain a final m-XDA hydrochloride composition. The m-XDA hydrochloridecomposition thus obtained was in a solid form of a pale yellow, theyield was 91%, and the water content was 3%.

Example A4

A 5-liter, 4-neck reactor was charged with 1,032.3 g (9.91 moles) of anaqueous solution of 35% hydrochloric acid, followed by lowering theinternal temperature of the reactor to 15° C. with stirring. While thetemperature of the reactor was maintained at 50° C., 600.0 g (4.4 moles)of m-XDA was introduced for 1 hour. Upon completion of the introduction,the internal temperature of the reactor was lowered to 10° C., and itwas stirred for 1 hour. Thereafter, 1,440 g of isobutanol (i-BuOH) as anorganic solvent was introduced, and the internal temperature of thereactor was lowered to −5° C., followed by stirring for 1 hour. Uponcompletion of the reaction, it was subjected to vacuum filtration usinga filter, and the filtered isobutanol was recovered for reuse. Therecovery rate of the isobutanol was 82%. Upon the vacuum filtration, am-XDA hydrochloride composition was obtained. In order to remove theresidual solvent and water, drying was performed under the conditions ofa reactor external temperature of 90° C. and a vacuum pump of 0.08 Torrto obtain a final m-XDA hydrochloride composition. The m-XDAhydrochloride composition thus obtained was in a solid form of a paleyellow, the yield was 92%, and the water content was 3%.

Example A5

A 5-liter, 4-neck reactor was charged with 1055.4 g (10.13 moles) of anaqueous solution of 35% hydrochloric acid, followed by lowering theinternal temperature of the reactor to 15° C. with stirring. While thetemperature of the reactor was maintained at 50° C., 600.0 g (4.4 moles)of m-XDA was introduced for 1 hour. Upon completion of the introduction,the internal temperature of the reactor was lowered to 10° C., and itwas stirred for 1 hour. Thereafter, 1,500 g of methyl ethyl ketone (MEK)as an organic solvent was introduced, and the internal temperature ofthe reactor was lowered to −5° C., followed by stirring for 1 hour. Uponcompletion of the reaction, it was subjected to vacuum filtration usinga filter, and the filtered methyl ethyl ketone was recovered for reuse.The recovery rate of the methyl ethyl ketone was 82%. Upon the vacuumfiltration, a m-XDA hydrochloride composition was obtained. In order toremove the residual solvent and water, drying was performed under theconditions of a reactor external temperature of 90° C. and a vacuum pumpof 0.05 Torr to obtain a final m-XDA hydrochloride composition. Them-XDA hydrochloride composition thus obtained was in a solid form of apale yellow, the yield was 92%, and the water content was 1%.

Example A6

Reactor 1 was charged with 1,009.4 g (9.46 moles) of an aqueous solutionof 35% hydrochloric acid, followed by lowering the internal temperatureof Reactor 1 to 15° C. with stirring. While the temperature of Reactor 1was maintained at 50° C. or lower, 627.0 g (4.4 moles) of H6XDA wasintroduced for 1 hour. Upon completion of the introduction, the internaltemperature of Reactor 1 was lowered to 10° C., and it was stirred for 1hour. The internal temperature of Reactor 2 to which 2,640.0 g ofdiethyl ether had been charged was lowered to −5° C. The mixture inReactor 1 was slowly added dropwise to Reactor 2 at 0° C. or lower. Uponcompletion of the addition, the diamine hydrochloride compositioncontaining H6XDA-2HCl was separated by vacuum filtration using a filter,and the filtered diethyl ether was recovered for reuse. Thereafter, theseparated diamine hydrochloride composition was dried under vacuum at90° C. and 0.5 torr to remove the residual solvent and water.

Example A7

A reactor was charged with 1,009.4 g (9.46 moles) of an aqueous solutionof 35% hydrochloric acid, followed by lowering the internal temperatureof the reactor to 15° C. with stirring. While the temperature of thereactor was maintained at 50° C. or lower, 490.1 g (4.4 moles) of HDAwas introduced for 1 hour. Upon completion of the introduction, theinternal temperature of the reactor was lowered to 10° C., and it wasstirred for 1 hour. Thereafter, 1,320.0 g of tetrahydrofuran wasintroduced, and the internal temperature of the reactor was lowered to−5° C., followed by stirring for 1 hour. Upon completion of thereaction, the diamine hydrochloride composition containing HDA.2HCl wasseparated by vacuum filtration using a filter, and the filteredtetrahydrofuran was recovered for reuse. Thereafter, the separateddiamine hydrochloride composition was dried under vacuum at 90° C. and0.5 torr to remove the residual solvent and water.

Example A8

Reactor 1 was charged with 1,009.4 g (9.46 moles) of an aqueous solutionof 35% hydrochloric acid, followed by lowering the internal temperatureof Reactor 1 to 15° C. with stirring. While the temperature of Reactor 1was maintained at 50° C. or lower, 812.0 g (4.4 moles) of IPDA wasintroduced for 1 hour. Upon completion of the introduction, the internaltemperature of Reactor 1 was lowered to 10° C., and it was stirred for 1hour. The internal temperature of Reactor 2 to which 2,640.0 g ofdiethyl ether had been charged was lowered to −5° C. The mixture inReactor 1 was slowly added dropwise to Reactor 2 at 0° C. or lower. Uponcompletion of the addition, the diamine hydrochloride compositioncontaining IPDA.2HCl was separated by vacuum filtration using a filter,and the filtered diethyl ether was recovered for reuse. Thereafter, theseparated diamine hydrochloride composition was dried under vacuum at90° C. and 0.5 torr to remove the residual solvent and water.

The process conditions of Examples A1 to A8 are summarized in Tables 1and 2 below.

TABLE 1 Ex. A1 Ex. A2 Ex. A3 Ex. A4 Ex. A5 Aqueous 963.5 g 986.5 g1,009.4 g 1,032.3 g 1,055.3 g hydrochloric acid solution Internal temp.50° C. 50° C. 50° C. 50° C. 50° C. of the reactor m-XDA   600 g   600 g  600 g   600 g   600 g Organic solvent Et₂O i-PrOH THF i-BuOH MEK 1,200g 1,260 g   1,320 g   1,440 g   1,500 g Vacuum condition 0.1 Torr 0.1Torr 0.1 Torr 0.08 Torr 0.05 Torr Yield of a 88% 88% 91% 92% 92%hydrochloride composition Water content in  2%  2%  3%  3%  1% thehydrochloride composition

TABLE 2 Ex. A6 Ex. A7 Ex. A8 Aqueous hydrochloric acid 1,009.4 g 1,009.4g 1009.4 g solution Internal temp. of the reactor 50° C. 50° C. 50° C.Diamine   627 g   490 g   812 g Organic solvent Diethyl ether, THFDiethyl ether,   2,640 g   1,320 g   2,640 g Yield of the hydrochloride70% 91% 72% composition

Preparation of a diisocyanate composition Examples 1-1 and 1-2

Reactor A was charged with 800 g of the m-XDA hydrochloride compositionprepared in Example A3 and 3,550 g of ODCB, which was heated at about125° C. with stirring. Reactor B was charged with 950 g of a triphosgene(BTMC) composition containing less than 1% by weight of carbontetrachloride (CCl₄) and 800 g of ODCB, which was stirred at about 60°C. for dissolution. While the temperature was maintained at 125° C. soas not to precipitate, it was added dropwise to Reactor A over 24 hours.Upon completion of the dropwise addition, it was stirred for 4 hours.Upon completion of the reaction, nitrogen gas was blown into the solventwith bubbling at 125° C. to degas. It was cooled to 10° C., and theremaining solids were filtered using celite. Thereafter, the organicsolvent (ODCB) was removed, and m-XDI was purified by distillation underthe following distillation conditions. The removal of the organicsolvent was carried out for 8 hours at a pressure of 0.5 torr or lessand a temperature of 60° C. In addition, the distillation of m-XDI wascarried out for 10 hours at a pressure of 0.5 torr or less and atemperature of 120° C.

Example 1-3

Reactor A was charged with 823 g of the diamine hydrochloridecomposition prepared in Example A6 and 3,550 g of ODCB, which was heatedat about 125° C. with stirring. Reactor B was charged with 950 g of atriphosgene (BTMC) composition containing less than 1% by weight ofcarbon tetrachloride (CCl₄) and 800 g of ODCB, which was stirred atabout 60° C. for dissolution. While the temperature was maintained at125° C. so as not to precipitate, it was added dropwise to Reactor Aover 24 hours. Upon completion of the dropwise addition, it was stirredfor 3 to 4 hours. Upon completion of the reaction, nitrogen gas wasblown into the solvent with bubbling at 125° C. to degas. Thereafter, itwas cooled to 10° C., and the remaining solids were filtered usingcelite. The organic solvent (ODCB) was removed, and distillation wascarried out to obtain a diisocyanate composition containing H6XDI. Here,the removal of the organic solvent was carried out for 8 hours at apressure of 0.5 torr or less and a temperature of 60° C. In addition,the distillation was carried out for 10 hours at a temperature of 120°C. and a pressure of 0.5 torr or less.

Example 1-4

Reactor A was charged with 723 g of the diamine hydrochloridecomposition prepared in Example A7 and 3,550 g of ODCB, which was heatedat about 125° C. with stirring. Reactor B was charged with 950 g of atriphosgene (BTMC) composition containing less than 1% by weight ofcarbon tetrachloride (CCl₄) and 800 g of ODCB, which was stirred atabout 60° C. for dissolution. While the temperature was maintained at125° C. so as not to precipitate, it was added dropwise to Reactor Aover 24 hours. Upon completion of the dropwise addition, it was stirredfor 3 to 4 hours. Upon completion of the reaction, nitrogen gas wasblown into the solvent with bubbling at 125° C. to degas. Thereafter, itwas cooled to 10° C., and the remaining solids were filtered usingcelite to obtain a diisocyanate composition containing HDI. Thereafter,the organic solvent in the diisocyanate composition was removed, anddistillation was carried out. Here, the removal of the organic solventwas carried out for 8 hours at a pressure of 0.5 torr or less and atemperature of 60° C. In addition, the distillation was carried out for10 hours at a temperature of 120° C. and a pressure of 0.5 torr or less.

Example 1-5

Reactor A was charged with 984 g of the diamine hydrochloridecomposition prepared in Example A8 and 3,550 g of ODCB, which was heatedat about 125° C. with stirring. Reactor B was charged with 950 g of atriphosgene (BTMC) composition containing less than 1% by weight ofcarbon tetrachloride (CCl₄) and 800 g of ODCB, which was stirred atabout 60° C. for dissolution. While the temperature was maintained at125° C. so as not to precipitate, it was added dropwise to Reactor Aover 24 hours. Upon completion of the dropwise addition, it was stirredfor 3 to 4 hours. Upon completion of the reaction, nitrogen gas wasblown into the solvent with bubbling at 125° C. to degas. Thereafter, itwas cooled to 10° C., and the remaining solids were filtered usingcelite to obtain a diisocyanate composition containing IPDI. Thereafter,the organic solvent in the diisocyanate composition was removed, anddistillation was carried out. Here, the removal of the organic solventwas carried out for 8 hours at a pressure of 0.5 torr or less and atemperature of 60° C. In addition, the distillation was carried out for10 hours at a temperature of 120° C. and a pressure of 0.5 torr or less.

Comparative Examples 1-1 and 1-2

The procedures of Example 1-1 were repeated, except that a diisocyanatecomposition was prepared using a triphosgene composition containing 1%by weight or more of carbon tetrachloride.

Comparative Example 1-3

The procedures of Example 1-3 were repeated, except that a diisocyanatecomposition was prepared using a triphosgene composition containing 1%by weight or more of carbon tetrachloride.

Comparative Example 1-4

The procedures of Example 1-4 were repeated, except that a diisocyanatecomposition was prepared using a triphosgene composition containing 1%by weight or more of carbon tetrachloride.

Comparative Example 1-5

The procedures of Example 1-5 were repeated, except that a diisocyanatecomposition was prepared using a triphosgene composition containing 1%by weight or more of carbon tetrachloride.

<Preparation of an Optical Lens>

As shown in Table 3 below, the diisocyanate composition (main component:m-XDI, H6XDI, HDI, or IPDI) prepared in the Examples or the ComparativeExamples, 5,7-dimercaptomethyl-1,11-dimercapto-3,6-trithiaundecane (BET)as a polythiol, and a tin-based catalyst as an additive were uniformlymixed and defoamed at 600 Pa for 1 hour to prepare a polymerizablecomposition.

The polymerizable composition was filtered through a Teflon filter of 3μm and injected into a glass mold assembled with an adhesive tape. Thepolymerizable composition injected into the mold was subjected to afirst polymerized at a temperature of 10 to 35° C. for 3 to 9 hours, asecond polymerization at a temperature of 35 to 60° C. for 3 to 9 hours,and a third polymerization at a temperature exceeding 60° C. for 2 to 7hours. Upon completion of the polymerization, the plastic molded article(optical lens) was released from the mold and subjected to furthercuring at 130° C. for 2 hours.

TABLE 3 Polvmerizable composition Diisocyanate composition Part by MainPolythiol (BET) Additive Type weight component Part by weight CatalystEx. 1-1 50.7 m-XDI 49.3 0.01 Ex. 1-2 50.7 m-XDI 49.3 0.01 Ex. 1-3 48.6H6XDI 51.4 0.05 Ex. 1-4 48.6 HDI 51.4 0.05 Ex. 1-5 48.2 IPDI 54.8 0.05C. Ex. 1-1 50.7 m-XDI 49.3 0.01 C. Ex. 1-2 50.7 m-XDI 49.3 0.01 C. Ex.1-3 48.6 H6XDI 51.4 0.05 C. Ex. 1-4 48.6 HDI 51.4 0.05 C. Ex. 1-5 48.2IPDI 54.8 0.05

<Evaluation Method>

The Examples and the Comparative Examples were evaluated as follows.

(1) Refractive Index (Nd20)

The solid-phase refractive index (nd20) was measured at 20° C. using anAbbe refractometer DR-M4.

(2) Yellow Index (Y.I.) and Light Transmittance

An optical lens was prepared in the form of a cylinder with a radius of16 mm and a height of 45 mm. Light was transmitted in the heightdirection to measure the yellow index and transmittance. The yellowindex was calculated by the following equation based on the values of xand y, which are the measurement results. Y.I.=(234x+106y)/y.

(3) Stria

A lens having a diameter of 75 mm with −2.00 and −8.00 D was prepared.Light from a mercury lamp as a light source was transmitted through thelens. The transmitted light was projected onto a white plate, and thepresence or absence of contrast was visually checked to determine thegeneration of striae.

(4) Measurement of ICP-MS

-   -   Analysis instrument: ICP-OES (Inductively Coupled Plasma-Optical        Emission Spectrometer)    -   Instrument detail: 730ES of Agilent    -   Light source: Axially viewed Plasma system    -   Detector: 167-785 nm wavelength CCD (charge coupled device)        detector    -   Pretreatment of a specimen: directly measured without        pretreatment

(5) APHA

A standard solution was prepared in 5 units of APHA in compliance withJIS K 0071-1 standard. The APHA value of the composition was comparedwith the prepared standard solution with the naked eyes, and the APHAvalue of the most similar color was taken.

(6) Haze

The optical lens was irradiated to a projector in a darkroom to observewhether the optical lens was cloudy or had any opaque material with thenaked eyes.

TABLE 4 BTMC Optical lens composition Diisocyanate compositionRefractive Content of CCl₄ APHA Haze Stria Transmittance Y.I. index Ex.1-1 0.2% by weight 5 Absent Absent 90% 18 1.669 Ex. 1-2 0.8% by weight 5Absent Absent 90% 19 1.669 Ex. 1-3 0.2% by weight 5 Absent Absent 91% 181.623 Ex. 1-4 0.2% by weight 5 Absent Absent 89% 19 1.624 Ex. 1-5 0.2%by weight 5 Absent Absent 90% 18 1.596 C. Ex. 1-1 1.5% by weight 15Present Present 77% 25 1.668 C. Ex. 1-2 2.1% by weight 20 PresentPresent 75% 27 1.668 C. Ex. 1-3 1.5% by weight 15 Present Present 75% 251.668 C. Ex. 1-4 1.5% by weight 15 Present Present 78% 26 1.668 C. Ex.1-5 1.5% by weight 15 Present Present 78% 26 1.668

As shown in the above table, the optical lenses prepared using a diaminehydrochloride and a triphosgene composition according to the Exampleswere excellent in refractive index and transmittance. Thus, they aresuitable for use as an optical lens of high quality.

In particular, in Examples 1-1 to 1-5 in which a triphosgene compositioncontaining less than 1% by weight of carbon tetrachloride was used toprepare a diisocyanate composition, the color and haze were excellent,and the optical lenses had no stria with high transmittance and lowyellow index.

In contrast, in Comparative Examples 1-1 to 1-5 in which a triphosgenecomposition containing 1% by weight or more of carbon tetrachloride wasused to prepare a diisocyanate composition, the color and haze werepoor, and the optical lenses had striae with low transmittance and highyellow index.

Preparation of a Diamine Hydrochloride Composition Examples A1 to A5

Tests were conducted in the same manner as in Examples A1 to A5.

Comparative Example A1

The same reactor as in Example A1 was charged with 846 g oforthodichlorobenzene (ODCB) as a reaction solvent. 136.2 g (1.0 mole) ofm-XDI and 621 g of ODCB were charged to the raw material tank (in atotal amine concentration of 8.5% by weight). Next, the internaltemperature of the reactor was raised to 120° C. under atmosphericpressure. Thereafter, hydrogen chloride gas began to be introducedthrough the hydrogen chloride gas injection line. At the same time, theentire amount of the amine diluted with the solvent was introduced fromthe raw material tank by a raw material charging pump over 2 hours. Uponcompletion of the reaction, the obtained hydrochloride slurry (yield90%) had low fluidity, and a large amount of the hydrochloridecomposition was left in the reactor in the process of separating thehydrochloride composition.

Comparative Example A2

The same procedures as in Example A1 were repeated, except that adiamine hydrochloride composition was prepared without using an organicsolvent (yield 49%).

TABLE 5 Ex. A1 Ex. A2 Ex. A3 Ex. A4 Ex. A5 C. Ex. A1 C. Ex. A2 Aqueous963.5 g 986.5 g 1,009.4 g 1,032.3 g 1,055.3 g HCl gas 963.5 ghydrochloric acid solution Internal temp. of the 50° C. 50° C. 50° C.50° C. 50° C. 120° C. 50° C. reactor m-XDA 600 g 600 g 600 g 600 g 600 g136.2 g 600 g Organic solvent Et₂O i-PrOH THF i-BuOH MEK ODCB — 1,200 g1,260 g 1,320 g 1,440 g 1,500 g 846 g + 621 g Vacuum condition 0.1 Torr0.1 Torr 0.1 Torr 0.08 Torr 0.05 Torr — 0.1 Torr Yield of the 88% 88%91% 92% 92% 90% 49% hydrochloride composition Water content in the  2% 2%  3%  3%  1% — — hydrochloride composition

Preparation of a Diisocyanate Composition Examples 2-1 to 2-3

Step (1): Preparation of a Triphosgene (BTMC) Composition

A commercially purchased triphosgene composition was dissolved inorthodichlorobenzene (ODCB) in 8% by weight. The b* value according tothe CIE color coordinate was measured. If it was 1.2 or less, thecomposition was used in the next step without separate treatment. If itexceeded 1.2, the composition was washed with a 10 to 30% sodiumchloride solution at 0° C. and then dried for 8 hours at 60° C. and 0.5Torr or less, whereby the b* value was adjusted to 1.2 or less (seeTable 6 below).

Step (2): Preparation of a m-XDI Composition

Reactor A was charged with 800 g of the m-XDA hydrochloride compositionprepared in Example A3 and 3,550 g of ODCB, which was heated at about125° C. with stirring. Reactor B was charged with 950 g of a triphosgene(BTMC) composition obtained in Step (1) and 800 g of ODCB, which wasstirred at about 60° C. for dissolution. While the temperature wasmaintained at 125° C. so as not to precipitate, it was added dropwise toReactor A over 24 hours. Upon completion of the dropwise addition, itwas stirred for 4 hours. Upon completion of the reaction, nitrogen gaswas blown into the solvent with bubbling at 125° C. to degas.Thereafter, it was cooled to 10° C., and the remaining solids werefiltered using celite. The filtered solvent and the produced m-XDI werepurified by distillation under the following distillation conditions.The removal of the organic solvent (ODCB) was carried out for 8 hours ata pressure of 0.5 torr or less and a temperature of 60° C. Thedistillation of m-XDI was carried out for 10 hours at a pressure of 0.1torr or less and a temperature of 120° C. As a result, a m-XDIcomposition was obtained.

Comparative Examples 2-1 and 2-2

The procedures of Example 2-1 were repeated, except that a m-XDIcomposition was prepared using a commercially purchased triphosgenecomposition without separate treatment. In such event, the b* valueaccording to the CIE color coordinate was 1.2 or more when thetriphosgene composition was dissolved in orthodichlorobenzene at aconcentration of 8% by weight.

<Preparation of an Optical Lens>

49.3 parts by weight of4,8-bis(mercaptomethyl)-3,6,9-trithiaundecane-1,11-dithiol, 50.7 partsby weight of the m-XDI composition prepared in the Examples or theComparative Examples, 0.01 part by weight of dibutyltin dichloride, and0.1 part by weight of a phosphate ester release agent (ZELEC™ UN Stepan)were homogeneously mixed, which was defoamed at 600 Pa for 1 hour,filtered through a Teflon filter of 3 μm, and injected into a mold madeof a glass mold and a tape. The mold was maintained at 25° C. for 8hours and slowly heated to 130° C. at a constant rate over 8 hours, andpolymerization was carried out at 130° C. for 2 hours. The moldedarticle was released from the mold and subjected to further curing at120° C. for 2 hours to obtain an optical lens.

<Evaluation Method>

The Examples and the Comparative Examples were evaluated as follows.

(1) Measurement of b*

The b* value was measured using a spectrophotometer (Colormate, SinkoCorporation). A liquid sample was filled in a quartz cell having athickness of 10 mm, and a solid sample was dissolved in an organicsolvent (ODCB) at 8% by weight. The lower the b* value, the better thecolor.

(2) Refractive Index (Nd20)

The solid-phase refractive index (nd20) was measured at 20° C. using anAbbe refractometer DR-M4.

(3) Yellow Index (Y.I.) and Light Transmittance

An optical lens was prepared in the form of a cylinder with a radius of16 mm and a height of 45 mm. Light was transmitted in the heightdirection to measure the yellow index and transmittance. The yellowindex was calculated by the following equation based on the values of xand y, which are the measurement results. Y.I.=(234x+106y)/y.

(4) Stria

A lens having a diameter of 75 mm with −2.00 and −8.00 D was prepared.Light from a mercury lamp as a light source was transmitted through thelens. The transmitted light was projected onto a white plate, and thepresence or absence of contrast was visually checked to determine thegeneration of striae.

(5) ICP-MS Measurement

-   -   Analysis instrument: ICP-OES (Inductively Coupled Plasma-Optical        Emission Spectrometer)    -   Instrument detail: 730ES of Agilent    -   Light source: Axially viewed Plasma system    -   Detector: 167-785 nm wavelength CCD (charge coupled device)        detector    -   Pretreatment of a specimen: directly measured without        pretreatment

(6) APHA

A standard solution was prepared in 5 units of APHA in compliance withJIS K 0071-1 standard. The APHA value of the composition was comparedwith the prepared standard solution with the naked eyes, and the APHAvalue of the most similar color was taken.

(7) Haze

The optical lens was irradiated to a projector in a darkroom to observewhether the optical lens was cloudy or had any opaque material with thenaked eyes.

TABLE 6 BTMC composition Before m-XDI Optical lens Initial BTMCintroduction composition Refractive b* washing b* APHA Haze StriaTransmittance Y.I. index Ex. 2-1 0.5 x 0.5 5 Absent Absent 90% 18 1.669Ex. 2-2 1.5 ∘ 0.5 5 Absent Absent 90% 18 1.669 Ex. 2-3 2.0 ∘ 0.7 5Absent Absent 88% 19 1.669 C. Ex. 2-1 1.5 x 1.5 15 Absent Absent 88% 321.668 C. Ex. 2-2 2.0 x 2.0 20 Absent Absent 85% 36 1.668

As shown in the above table, the optical lenses prepared using a diaminehydrochloride and a triphosgene composition according to the Exampleswere excellent in refractive index and transmittance. Thus, they aresuitable for use as an optical lens of high quality.

In particular, in Examples 2-1 to 2-3 in which a triphosgene compositionhaving a b* value of less than 1.2 was used to prepare a diisocyanatecomposition, the color and haze were excellent, and the optical lenseshad no stria with high transmittance and low yellow index.

In contrast, in Comparative Examples 2-1 and 2-2 in which a triphosgenecomposition having a b* value of 1.2 or more was used to prepare adiisocyanate composition, the color and haze were poor, and the opticallenses had low transmittance and high yellow index.

Preparation Example: Adjustment of the Content of Water in BTMC

The content of water in triphosgene (BTMC) to be used in the reactionwas measured. If it was 200 ppm or less, the triphosgene was used in thereaction as it was. If it exceeded 200 ppm, the water content wasadjusted by washing and/or drying it under the conditions shown in Table7 below.

The procedures for measuring the water content were as follows. First,the Karl Fischer reagent for the measurement of moisture was filled in avaporized moisture meter (KEM, MKS-710S) installed in a glove box filledwith dried nitrogen. The flow rate of nitrogen gas was 200 ml/minute,and the internal sublimation temperature was set to 120° C. Preliminarytitration was performed to stabilize it until the draft value became0.10 μg/s or less. Then, the moisture content was measured (back purge30 minutes, cell purge 30 minutes, measurement time 40 minutes).

TABLE 7 Content of water in BTMC drying (ppm) Washing Temp. Time InitialFinal Solvent (° C.) (hr) Prep. Ex. A 20 20 — — — Prep. Ex. B 311 25 THF60 4 Prep. Ex. C 311 15 — 60 8 Prep. Ex. D 311 56 THF 20 8 Prep. Ex. E311 45 Acetone 50 4 Prep, Ex. F 311 311 — — — Prep. Ex. G 311 256 — 5 8Prep. Ex. H 311 29 THF 100 4 Prep. Ex. I 311 222 Cyclohexanone 60 8Prep. Ex. J 311 240 Pyridine 60 8

Examples 3-1 to 3-5: Preparation of a Diisocyanate Composition

Step (1): Preparation of a Diamine Hydrochloride Composition

A reactor was charged with 1,009.4 g (9.46 moles) of an aqueous solutionof 35% hydrochloric acid, followed by lowering the internal temperatureof the reactor to 15° C. with stirring. While the temperature of thereactor was maintained at 60° C., 600.0 g (4.4 moles) of m-XDA wasintroduced for 1 hour. Upon completion of the introduction, the internaltemperature of the reactor was lowered to 10° C., and it was stirred for1 hour. Thereafter, 1,500.0 g of tetrahydrofuran (THF) was introduced,and the internal temperature of the reactor was lowered to −5° C.,followed by stirring for 1 hour. Upon completion of the reaction, thediamine hydrochloride composition containing m-XDA.2HCl was separated byvacuum filtration using a filter, and the filtered tetrahydrofuran wasrecovered for reuse. In order to remove the residual solvent and water,the separated diamine hydrochloride composition was vacuum dried at 90°C. and 0.5 torr.

Step (2): Preparation of a Diisocyanate Composition

Reactor A was charged with 800 g of the diamine hydrochloridecomposition prepared above and 3,550 g of ODCB, which were heated atabout 125° C. with stirring. Reactor B was charged with 950 g oftriphosgene (BTMC of Preparation Examples A to E) whose water contenthad been adjusted and 800 g of ODCB, which was stirred at about 60° C.for dissolution. While the temperature was maintained at 125° C. so asnot to precipitate, it was added dropwise to Reactor A over 24 hours.Upon completion of the dropwise addition, it was stirred for 4 hours.Upon completion of the reaction, nitrogen gas was blown into the solventwith bubbling at 125° C. to degas. Thereafter, it was cooled to 10° C.,and the remaining solids were filtered using celite. The organic solvent(ODCB) was removed, and distillation was carried out to obtain adiisocyanate composition containing m-XDI. Here, the removal of theorganic solvent was carried out for 8 hours at a pressure of 0.5 torr orless and a temperature of 60° C. The distillation was carried out for 10hours at a pressure of 0.5 torr or less and a temperature of 120° C.

Comparative Examples 3-1 to 3-5: Preparation of a DiisocyanateComposition

The same procedures as in the above examples were repeated, except that,as the triphosgene used in step (2), the triphosgene (BTMC ofPreparation Example F) whose water content had not been adjusted or thetriphosgene (Preparation Examples G to J), which had not been properlywashed or dried to control the water content, was used to prepare adiisocyanate composition.

Example 3-6

Step (1): Preparation of a Diamine Hydrochloride Composition

Reactor 1 was charged with 1,009.4 g (9.46 moles) of an aqueous solutionof 35% hydrochloric acid, followed by lowering the internal temperatureof Reactor 1 to 15° C. with stirring. While the temperature of Reactor 1was maintained at 50° C. or lower, 627.0 g (4.4 moles) of H6XDA wasintroduced for 1 hour. Upon completion of the introduction, the internaltemperature of Reactor 1 was lowered to 10° C., and it was stirred for 1hour. The internal temperature of Reactor 2 to which 2,640.0 g ofdiethyl ether had been charged was lowered to −5° C. The mixture inReactor 1 was slowly added dropwise to Reactor 2 at 0° C. or lower. Uponcompletion of the addition, the diamine hydrochloride compositioncontaining H6XDA-2HCl was separated by vacuum filtration using a filter,and the filtered diethyl ether was recovered for reuse. Thereafter, theseparated diamine hydrochloride composition was dried under vacuum at90° C. and 0.5 torr to remove the residual solvent and water.

Step (2): Preparation of a Diisocyanate Composition

Reactor A was charged with 823 g of the diamine hydrochloridecomposition prepared above and 3,550 g of ODCB, which was heated atabout 125° C. with stirring. Reactor B was charged with 950 g oftriphosgene (BTMC of Preparation Example A) and 800 g of ODCB, which wasstirred at about 60° C. for dissolution. While the temperature wasmaintained at 125° C. so as not to precipitate, it was added dropwise toReactor A over 24 hours. Upon completion of the dropwise addition, itwas stirred for 3 to 4 hours. Upon completion of the reaction, nitrogengas was blown into the solvent with bubbling at 125° C. to degas.Thereafter, it was cooled to 10° C., and the remaining solids werefiltered using celite. The organic solvent (ODCB) was removed, anddistillation was carried out to obtain a diisocyanate compositioncontaining H6XDI. Here, the removal of the organic solvent was carriedout for 8 hours at a pressure of 0.5 torr or less and a temperature of60° C. In addition, the distillation was carried out for 10 hours at atemperature of 120° C. and a pressure of 0.5 torr or less.

Example 3-7

Step (1): Preparation of a Diamine Hydrochloride Composition

A reactor was charged with 1,009.4 g (9.46 moles) of an aqueous solutionof 35% hydrochloric acid, followed by lowering the internal temperatureof the reactor to 15° C. with stirring. While the temperature of thereactor was maintained at 50° C. or lower, 490.1 g (4.4 moles) of HDAwas introduced for 1 hour. Upon completion of the introduction, theinternal temperature of the reactor was lowered to 10° C., and it wasstirred for 1 hour. Thereafter, 1,320.0 g of tetrahydrofuran wasintroduced, and the internal temperature of the reactor was lowered to−5° C., followed by stirring for 1 hour. Upon completion of thereaction, the diamine hydrochloride composition containing HDA.2HCl wasseparated by vacuum filtration using a filter, and the filteredtetrahydrofuran was recovered for reuse. Thereafter, the separateddiamine hydrochloride composition was dried under vacuum at 90° C. and0.5 torr to remove the residual solvent and water.

Step (2): Preparation of a Diisocyanate Composition

Reactor A was charged with 723 g of the diamine hydrochloridecomposition prepared above and 3,550 g of ODCB, which was heated atabout 125° C. with stirring. Reactor B was charged with 950 g oftriphosgene (BTMC of Preparation Example A) and 800 g of ODCB, which wasstirred at about 60° C. for dissolution. While the temperature wasmaintained at 125° C. so as not to precipitate, it was added dropwise toReactor A over 24 hours. Upon completion of the dropwise addition, itwas stirred for 3 to 4 hours. Upon completion of the reaction, nitrogengas was blown into the solvent with bubbling at 125° C. to degas.Thereafter, it was cooled to 10° C., and the remaining solids werefiltered using celite to obtain a diisocyanate composition containingHDI. Thereafter, the organic solvent in the diisocyanate composition wasremoved, and distillation was carried out. Here, the removal of theorganic solvent was carried out for 8 hours at a pressure of 0.5 torr orless and a temperature of 60° C. In addition, the distillation wascarried out for 10 hours at a temperature of 120° C. and a pressure of0.5 torr or less.

Example 3-8

Step (1): Preparation of a Diamine Hydrochloride Composition

Reactor 1 was charged with 1,009.4 g (9.46 moles) of an aqueous solutionof 35% hydrochloric acid, followed by lowering the internal temperatureof Reactor 1 to 15° C. with stirring. While the temperature of Reactor 1was maintained at 50° C. or lower, 812.0 g (4.4 moles) of IPDA wasintroduced for 1 hour. Upon completion of the introduction, the internaltemperature of Reactor 1 was lowered to 10° C., and it was stirred for 1hour. The internal temperature of Reactor 2 to which 2,640.0 g ofdiethyl ether had been charged was lowered to −5° C. The mixture inReactor 1 was slowly added dropwise to Reactor 2 at 0° C. or lower. Uponcompletion of the addition, the diamine hydrochloride compositioncontaining IPDA.2HCl was separated by vacuum filtration using a filter,and the filtered diethyl ether was recovered for reuse. Thereafter, theseparated diamine hydrochloride composition was dried under vacuum at90° C. and 0.5 torr to remove the residual solvent and water.

Step (2): Preparation of a Diisocyanate Composition

Reactor A was charged with 984 g of the diamine hydrochloridecomposition prepared above and 3,550 g of ODCB, which was heated atabout 125° C. with stirring. Reactor B was charged with 950 g oftriphosgene (BTMC of Preparation Example A) and 800 g of ODCB, which wasstirred at about 60° C. for dissolution. While the temperature wasmaintained at 125° C. so as not to precipitate, it was added dropwise toReactor A over 24 hours. Upon completion of the dropwise addition, itwas stirred for 3 to 4 hours. Upon completion of the reaction, nitrogengas was blown into the solvent with bubbling at 125° C. to degas.Thereafter, it was cooled to 10° C., and the remaining solids werefiltered using celite to obtain a diisocyanate composition containingIPDI. Thereafter, the organic solvent in the diisocyanate compositionwas removed, and distillation was carried out. Here, the removal of theorganic solvent was carried out for 8 hours at a pressure of 0.5 torr orless and a temperature of 60° C. In addition, the distillation wascarried out for 10 hours at a temperature of 120° C. and a pressure of0.5 torr or less.

Comparative Example 3-6

The same procedures as in Example 3-6 were repeated, except that, as thetriphosgene used in step (2), the triphosgene (BTMC of PreparationExample F) whose water content had not been adjusted was used to preparea diisocyanate composition.

Comparative Example 3-7

The same procedures as in Example 3-7 were repeated, except that, as thetriphosgene used in step (2), the triphosgene (BTMC of PreparationExample F) whose water content had not been adjusted was used to preparea diisocyanate composition.

Comparative Example 3-8

The same procedures as in Example 3-8 were repeated, except that, as thetriphosgene used in step (2), the triphosgene (BTMC of PreparationExample F) whose water content had not been adjusted was used to preparea diisocyanate composition.

<Preparation of an Optical Lens>

As shown in Table 8 below, the diisocyanate composition (main component:m-XDI, H6XDI, HDI, or IPDI) prepared in the Examples or the ComparativeExamples, 5,7-dimercaptomethyl-1,11-dimercapto-3,6-trithiaundecane (BET)as a polythiol, and a tin-based catalyst as an additive were uniformlymixed and defoamed at 600 Pa for 1 hour to prepare a polymerizablecomposition.

The polymerizable composition was filtered through a Teflon filter of 3μm and injected into a glass mold assembled with an adhesive tape. Thepolymerizable composition injected into the mold was subjected to afirst polymerized at a temperature of 10° C. to 35° C. for 3 hours to 9hours, a second polymerization at a temperature of 35° C. to 60° C. for3 hours to 9 hours, and a third polymerization at a temperatureexceeding 60° C. for 2 to 7 hours. Upon completion of thepolymerization, the plastic molded article (optical lens) was releasedfrom the mold and subjected to further curing at 130° C. for 2 hours.

BET:

5,7-dimercaptomethyl-1,11-dimercapto-3,6-trithiaundecane

m-XDI:

m-xylylene diisocyanate

H6XDI:

hydrogenated xylylene diisocyanate

HDI:

hexamethylene diisocyanate

IPDI:

isophorone diisocyanate

TABLE 8 Polymerizable composition Diisocyanate composition Part by MainPolythiol (BET) Additive Type weight component Part by weight CatalystEx. 3-1 50.7 m-XDI 49.3 0.01 Ex. 3-2 50.7 m-XDI 49.3 0.01 Ex. 3-3 50.7m-XDI 49.3 0.01 Ex. 3-4 50.7 m-XDI 49.3 0.01 Ex. 3-5 50.7 m-XDI 49.30.01 Ex. 3-6 48.6 H6XDI 51.4 0.05 Ex. 3-7 48.6 HDI 51.4 0.05 Ex. 3-848.2 IPDI 54.8 0.05 C. Ex. 3-1 50.7 m-XDI 49.3 0.01 C. Ex. 3-2 50.7m-XDI 49.3 0.01 C. Ex. 3-3 50.7 m-XDI 49.3 0.01 C. Ex. 3-4 50.7 m-XDI49.3 0.01 C. Ex. 3-5 50.7 m-XDI 49.3 0.01 C. Ex. 3-6 48.6 H6XDI 51.40.05 C. Ex. 3-7 48.6 HDI 51.4 0.05 C. Ex. 3-8 48.2 IPDI 54.8 0.05

Evaluation Method

The diisocyanate compositions and optical lenses prepared in theExamples and the Comparative Examples were evaluated as follows.

(1) Content of a Diisocyanate

The content of a diisocyanate in the diisocyanate composition wasdetermined by gas chromatography (GC) (instrument: 6890/7890 of Agilent,carrier gas: He, injection temperature 250° C., oven temperature 40° C.to 320° C., column: HP-1, Wax, 30 m, detector: FID, 300° C.)

(2) Distillation Yield

The distillation yield was calculated by measuring the amount of thediisocyanate composition upon the distillation relative to thetheoretical amount of the diisocyanate composition produced from theamounts of the diamine hydrochloride composition introduced to thereaction with triphosgene.

(3) Stria

A lens having a diameter of 75 mm with −2.00 and −8.00 D was prepared.Light from a mercury lamp as a light source was transmitted through thelens. The transmitted light was projected onto a white plate, and thepresence or absence of contrast was visually checked to determine thegeneration of striae.

(4) Yellow Index (Y.I.)

An optical lens was prepared in the form of a cylinder with a radius of16 mm and a height of 45 mm. Light was transmitted in the heightdirection to measure the yellow index. The yellow index was calculatedby the following equation based on the values of x and y, which are themeasurement results. Y.I.=(234x+106y)/y.

(5) Cloudiness (Haze)

The optical lens was irradiated to a projector in a darkroom to observewhether the optical lens was cloudy or had any opaque material with thenaked eyes.

TABLE 9 Content of a diisocyanate in the diisocyanate compositionDistillation (% by weight) yield Before After Optical lens BTMC (%)distillation distillation Stria Cloudiness Y.I. Ex. 3-1 Prep. Ex. A 8999.4 99.9 Absent Absent 19 Ex. 3-2 Prep. Ex. B 88 99.3 99.9 AbsentAbsent 20 Ex. 3-3 Prep. Ex. C 89 99.2 99.9 Absent Absent 19 Ex. 3-4Prep. Ex. D 87 99.3 99.9 Absent Absent 20 Ex. 3-5 Prep. Ex. E 89 99.399.9 Absent Absent 20 Ex. 3-6 Prep. Ex. A 88 99.2 99.8 Absent Absent 19Ex. 3-7 Prep. Ex. A 89 99.1 99.8 Absent Absent 20 Ex. 3-8 Prep. Ex. A 8999.0 99.8 Absent Absent 19 C. Ex. 3-1 Prep. Ex. F 75 98.3 99.2 AbsentSlight haze 22 C. Ex. 3-2 Prep. Ex. G 84 98.5 99.5 Absent Slight haze 23C. Ex. 3-3 Prep. Ex. H 86 98.1 99.5 Absent Slight haze 22 C. Ex. 3-4Prep. Ex. I 84 98.3 99.6 Absent Slight haze 21 C. Ex. 3-5 Prep. Ex. JReaction failing to be carried out C. Ex. 3-6 Prep. Ex. F 78 98.1 99.3Absent Slight haze 23 C. Ex. 3-7 Prep. Ex. F 77 98.2 99.2 Absent Slighthaze 22 C. Ex. 3-8 Prep. Ex. F 79 98.4 99.1 Absent Slight haze 24

As can be seen from the above table, in Examples 3-1 to 3-8 in whichtriphosgene (Preparation Examples A to E) whose water content had beenadjusted was used, the distillation yield and the content of adiisocyanate in the composition were excellent. The optical lensesprepared therefrom were improved in stria, cloudiness, and yellow index.

In contrast, in Comparative Examples 3-1 and 3-6 to 3-8 in whichtriphosgene (Preparation Example F) whose water content had not beenadjusted was used, or in Comparative Examples 3-2 to 3-5 in whichtriphosgene (Preparation Examples G to J), which had not been properlywashed or dried to control the water content, was used, the phosgenationreaction failed to be carried out, or the distillation yield and thecontent of a diisocyanate in the composition were poor. The opticallenses prepared therefrom had cloudiness and yellowing.

1. A process for preparing a diisocyanate composition, which comprises:reacting a diamine hydrochloride composition with a triphosgenecomposition to obtain a diisocyanate composition, wherein the content ofa decomposition product of triphosgene in the triphosgene composition isless than 1% by weight.
 2. The process for preparing a diisocyanatecomposition of claim 1, wherein the decomposition product of triphosgenecomprises carbon tetrachloride, and the content of the decompositionproduct of triphosgene in the triphosgene composition is adjusted bywashing the triphosgene composition with diethyl ether at 5σC or lower.3. The process for preparing a diisocyanate composition of claim 1,wherein the diamine hydrochloride composition and the triphosgenecomposition are introduced to the reaction at an equivalent ratio of 1:1to 5, and the reaction of the diamine hydrochloride composition and thetriphosgene composition is carried out at a temperature of 110° C. to160° C.
 4. The process for preparing a diisocyanate composition of claim1, wherein the diisocyanate composition is obtained by subjecting thereaction resultant obtained by reacting the diamine hydrochloridecomposition and the triphosgene composition to first distillation at 40°C. to 60° C. for 2 to 8 hours and second distillation at 80° C. to 160°C. for 2 to 10 hours.
 5. The process for preparing a diisocyanatecomposition of claim 1, wherein the diisocyanate composition has an APHAvalue of 10 or less, the diamine is xylylenediamine, and thediisocyanate composition comprises xylylene diisocyanate.
 6. The processfor preparing a diisocyanate composition of claim 1, wherein the diaminehydrochloride composition is obtained by reacting a diamine with anaqueous hydrochloric acid solution, the aqueous hydrochloric acidsolution has a concentration of 20% by weight to 45% by weight, and thediamine and the aqueous hydrochloric acid solution are introduced to thereaction at an equivalent ratio of 1:2 to 5 at a temperature of 20° C.to 40° C.
 7. A process for preparing a diisocyanate composition, whichcomprises: reacting a diamine hydrochloride composition with atriphosgene composition to obtain a diisocyanate composition, whereinthe triphosgene composition has a b* value according to the CIE colorcoordinate of 1.2 or less when dissolved in orthodichlorobenzene at aconcentration of 8% by weight.
 8. The process for preparing adiisocyanate composition of claim 7, wherein the b* value according tothe CIE color coordinate of the triphosgene composition is adjusted bywashing the triphosgene composition with a 10% to 30% sodium chloridesolution.
 9. A process for preparing a diisocyanate composition, whichcomprises: reacting a diamine with an aqueous hydrochloric acid solutionto obtain a diamine hydrochloride composition, and reacting the diaminehydrochloride composition with triphosgene to obtain a diisocyanatecomposition, wherein the content of water in the triphosgene compositionis 200 ppm or less.
 10. The process for preparing a diisocyanatecomposition of claim 9, wherein the content of water in the triphosgeneis adjusted through a further step of at least one of washing anddrying, and the content of water in the triphosgene is 50 ppm or lessafter the further step.
 11. The process for preparing a diisocyanatecomposition of claim 9, wherein the triphosgene is washed with a solventhaving a polarity index of 3.9 to 5.7 before the triphosgene isintroduced to the reaction, the solvent has a boiling point of 85° C. orlower, and the solvent is a compound that does not have a hydroxyl groupor an amine group and comprises at least one of tetrahydrofuran andacetone.
 12. The process for preparing a diisocyanate composition ofclaim 10, wherein the triphosgene, after the washing, is further driedunder the conditions of a temperature of 20° C. to 60° C. and a pressureof 0.01 torr to 100 torr, and the content of the residual solvents usedin the washing in the triphosgene, after the drying, is less than 100ppm.
 13. The process for preparing a diisocyanate composition of claim9, wherein the triphosgene is dried for 2 hours to 10 hours under theconditions of a temperature of 20° C. to 60° C. and a pressure of 0.01torr to 100 torr before the triphosgene is introduced to the reaction,the diisocyanate composition is obtained by distillation after thereaction of the diamine hydrochloride composition and triphosgene, thedistillation comprises distillation of a diisocyanate at a temperatureof 100° C. to 130° and a pressure of 2 torr or less, the yield of thedistillation of a diisocyanate is 87% or more, and the diisocyanatecomposition, after the distillation of a diisocyanate, comprises thediisocyanate in an amount of 99.9% by weight or more.